From df5988bacfd720bbcd0cf6e047ead7568f75e66d Mon Sep 17 00:00:00 2001
From: Matthew Glazar <strager.nds@gmail.com>
Date: Wed, 3 Jan 2018 20:07:54 -0800
Subject: [PATCH] Refactor some code to use randomChance

Mechanically refactor code which uses PRNG#random for booleans to use
PRNG#randomChance instead.

Take advantage of the following properties:

    random(x) < y        is equivalent to   randomChance(y, x)
    random(x) <= y       is equivalent to   random(x) < (y + 1), i.e. randomChance(y + 1, x)
    random(x) >= y       is equivalent to   !(random(x) < y), i.e. !randomChance(y, x)
    random(x) > y        is equivalent to   random(x) >= (y + 1), i.e. !randomChance(y + 1, x)
    random(x) === 0      is equivalent to   random(x) < 1, i.e. randomChance(1, x)
    !random(x)           is equivalent to   random(x) === 0, i.e. randomChance(1, x)
    Boolean(random(x))   is equivalent to   random(x) > 0, i.e. !randomChance(1, x)

This commit should not change behaviour. In particular, PRNG#next is
called the same number of times with the same number of parameter as
before this commit, and PRNG#next's results are interpreted in the same
way as before this commit.
---
 data/random-teams.js      | 44 +++++++++++++++++++--------------------
 data/scripts.js           |  4 ++--
 data/statuses.js          |  4 ++--
 mods/gen1/random-teams.js |  2 +-
 mods/gen1/scripts.js      |  6 +++---
 mods/gen1/statuses.js     |  2 +-
 mods/gen2/random-teams.js |  2 +-
 mods/gen2/scripts.js      |  6 +++---
 mods/gen2/statuses.js     |  2 +-
 mods/gen3/random-teams.js |  8 +++----
 mods/gen4/random-teams.js |  8 +++----
 mods/gen5/random-teams.js | 14 ++++++-------
 mods/gen5/statuses.js     |  2 +-
 mods/gen6/random-teams.js | 20 +++++++++---------
 mods/stadium/scripts.js   |  6 +++---
 sim/battle.js             |  2 +-
 16 files changed, 66 insertions(+), 66 deletions(-)

diff --git a/data/random-teams.js b/data/random-teams.js
index 02578d3eab..1846ef2a16 100644
--- a/data/random-teams.js
+++ b/data/random-teams.js
@@ -1133,12 +1133,12 @@ class RandomTeams extends Dex.ModdedDex {
 		let ability1 = this.getAbility(abilities[1]);
 		let ability2 = this.getAbility(abilities[2]);
 		if (abilities[1]) {
-			if (abilities[2] && ability1.rating <= ability2.rating && this.random(2)) {
+			if (abilities[2] && ability1.rating <= ability2.rating && !this.randomChance(1, 2)) {
 				[ability1, ability2] = [ability2, ability1];
 			}
-			if (ability0.rating <= ability1.rating && this.random(2)) {
+			if (ability0.rating <= ability1.rating && !this.randomChance(1, 2)) {
 				[ability0, ability1] = [ability1, ability0];
-			} else if (ability0.rating - 0.6 <= ability1.rating && this.random(3)) {
+			} else if (ability0.rating - 0.6 <= ability1.rating && !this.randomChance(1, 3)) {
 				[ability0, ability1] = [ability1, ability0];
 			}
 			ability = ability0.name;
@@ -1261,7 +1261,7 @@ class RandomTeams extends Dex.ModdedDex {
 				ability = 'Pickup';
 			} else if (template.baseSpecies === 'Basculin') {
 				ability = 'Adaptability';
-			} else if (template.species === 'Lopunny' && hasMove['switcheroo'] && this.random(3)) {
+			} else if (template.species === 'Lopunny' && hasMove['switcheroo'] && !this.randomChance(1, 3)) {
 				ability = 'Klutz';
 			} else if ((template.species === 'Rampardos' && !hasMove['headsmash']) || hasMove['rockclimb']) {
 				ability = 'Sheer Force';
@@ -1340,7 +1340,7 @@ class RandomTeams extends Dex.ModdedDex {
 			// To perma-taunt a Pokemon by giving it Assault Vest
 			item = 'Assault Vest';
 		} else if (hasMove['switcheroo'] || hasMove['trick']) {
-			let randomNum = this.random(3);
+			let randomNum = !this.randomChance(1, 3);
 			if (counter.Physical >= 3 && (template.baseStats.spe < 60 || template.baseStats.spe > 108 || randomNum)) {
 				item = 'Choice Band';
 			} else if (counter.Special >= 3 && (template.baseStats.spe < 60 || template.baseStats.spe > 108 || randomNum)) {
@@ -1363,7 +1363,7 @@ class RandomTeams extends Dex.ModdedDex {
 		} else if (hasMove['bellydrum']) {
 			if (ability === 'Gluttony') {
 				item = ['Aguav', 'Figy', 'Iapapa', 'Mago', 'Wiki'][this.random(5)] + ' Berry';
-			} else if (template.baseStats.spe <= 50 && !teamDetails.zMove && this.random(2)) {
+			} else if (template.baseStats.spe <= 50 && !teamDetails.zMove && !this.randomChance(1, 2)) {
 				item = 'Normalium Z';
 			} else {
 				item = 'Sitrus Berry';
@@ -1401,10 +1401,10 @@ class RandomTeams extends Dex.ModdedDex {
 		} else if (template.baseStats.spe <= 50 && hasMove['sleeppowder'] && counter.setupType && !teamDetails.zMove) {
 			item = 'Grassium Z';
 		} else if (counter.Physical >= 4 && !hasMove['bodyslam'] && !hasMove['dragontail'] && !hasMove['fakeout'] && !hasMove['flamecharge'] && !hasMove['rapidspin'] && !hasMove['suckerpunch']) {
-			item = template.baseStats.atk >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && this.random(3) ? 'Choice Scarf' : 'Choice Band';
+			item = template.baseStats.atk >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !this.randomChance(1, 3) ? 'Choice Scarf' : 'Choice Band';
 		} else if (counter.Special >= 4 && !hasMove['acidspray'] && !hasMove['chargebeam'] && !hasMove['clearsmog'] && !hasMove['fierydance']) {
-			item = template.baseStats.spa >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && this.random(3) ? 'Choice Scarf' : 'Choice Specs';
-		} else if (((counter.Physical >= 3 && hasMove['defog']) || (counter.Special >= 3 && hasMove['uturn'])) && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && this.random(3)) {
+			item = template.baseStats.spa >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !this.randomChance(1, 3) ? 'Choice Scarf' : 'Choice Specs';
+		} else if (((counter.Physical >= 3 && hasMove['defog']) || (counter.Special >= 3 && hasMove['uturn'])) && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !this.randomChance(1, 3)) {
 			item = 'Choice Scarf';
 		} else if (ability === 'Defeatist' || hasMove['eruption'] || hasMove['waterspout']) {
 			item = counter.Status <= 1 ? 'Expert Belt' : 'Leftovers';
@@ -1420,7 +1420,7 @@ class RandomTeams extends Dex.ModdedDex {
 			item = 'Leftovers';
 		} else if (hasMove['substitute']) {
 			item = !counter['drain'] || counter.damagingMoves.length < 2 ? 'Leftovers' : 'Life Orb';
-		} else if ((ability === 'Iron Barbs' || ability === 'Rough Skin') && this.random(2)) {
+		} else if ((ability === 'Iron Barbs' || ability === 'Rough Skin') && !this.randomChance(1, 2)) {
 			item = 'Rocky Helmet';
 		} else if (counter.Physical + counter.Special >= 4 && template.baseStats.spd >= 65 && template.baseStats.hp + template.baseStats.def + template.baseStats.spd >= 235) {
 			item = 'Assault Vest';
@@ -1729,7 +1729,7 @@ class RandomTeams extends Dex.ModdedDex {
 			species = template.baseSpecies;
 		}
 		let battleForme = this.checkBattleForme(template);
-		if (battleForme && (battleForme.isMega ? !teamDetails.megaStone : this.random(2))) {
+		if (battleForme && (battleForme.isMega ? !teamDetails.megaStone : !this.randomChance(1, 2))) {
 			template = this.getTemplate(template.otherFormes.length >= 2 ? template.otherFormes[this.random(template.otherFormes.length)] : template.otherFormes[0]);
 		}
 
@@ -2183,10 +2183,10 @@ class RandomTeams extends Dex.ModdedDex {
 		ability = ability0.name;
 		if (abilities[1]) {
 			if (abilities[2] && ability2.rating === ability1.rating) {
-				if (this.random(2)) ability1 = ability2;
+				if (!this.randomChance(1, 2)) ability1 = ability2;
 			}
 			if (ability0.rating <= ability1.rating) {
-				if (this.random(2)) ability = ability1.name;
+				if (!this.randomChance(1, 2)) ability = ability1.name;
 			} else if (ability0.rating - 0.6 <= ability1.rating) {
 				if (this.randomChance(1, 3)) ability = ability1.name;
 			}
@@ -2328,7 +2328,7 @@ class RandomTeams extends Dex.ModdedDex {
 		} else if (template.species === 'Unown') {
 			item = 'Choice Specs';
 		} else if (hasMove['trick'] || hasMove['switcheroo']) {
-			let randomNum = this.random(2);
+			let randomNum = !this.randomChance(1, 2);
 			if (counter.Physical >= 3 && (template.baseStats.spe >= 95 || randomNum)) {
 				item = 'Choice Band';
 			} else if (counter.Special >= 3 && (template.baseStats.spe >= 95 || randomNum)) {
@@ -2339,7 +2339,7 @@ class RandomTeams extends Dex.ModdedDex {
 		} else if (ability === 'Gluttony' || ability === 'Schooling') {
 			item = ['Aguav', 'Figy', 'Iapapa', 'Mago', 'Wiki'][this.random(5)] + ' Berry';
 		} else if (hasMove['bellydrum']) {
-			if (template.baseStats.spe <= 50 && !teamDetails.zMove && this.random(2)) {
+			if (template.baseStats.spe <= 50 && !teamDetails.zMove && !this.randomChance(1, 2)) {
 				item = 'Normalium Z';
 			} else {
 				item = 'Sitrus Berry';
@@ -2536,7 +2536,7 @@ class RandomTeams extends Dex.ModdedDex {
 			ivs: ivs,
 			item: item,
 			level: level,
-			shiny: !this.random(template.id === 'missingno' ? 4 : 1024),
+			shiny: this.randomChance(1, template.id === 'missingno' ? 4 : 1024),
 		};
 	}
 	randomFactorySet(template, slot, teamData, tier) {
@@ -2625,7 +2625,7 @@ class RandomTeams extends Dex.ModdedDex {
 		return {
 			name: setData.set.name || template.baseSpecies,
 			species: setData.set.species,
-			gender: setData.set.gender || template.gender || (this.random(2) ? 'M' : 'F'),
+			gender: setData.set.gender || template.gender || (!this.randomChance(1, 2) ? 'M' : 'F'),
 			item: items + '' || setData.set.item || '',
 			ability: abilities + '' || setData.set.ability || template.abilities['0'],
 			shiny: typeof setData.set.shiny === 'undefined' ? this.randomChance(1, 1024) : setData.set.shiny,
@@ -2691,7 +2691,7 @@ class RandomTeams extends Dex.ModdedDex {
 			// If not Monotype, limit to two of each type
 				let skip = false;
 				for (let t = 0; t < types.length; t++) {
-					if (teamData.typeCount[types[t]] > 1 && this.random(5)) {
+					if (teamData.typeCount[types[t]] > 1 && !this.randomChance(1, 5)) {
 						skip = true;
 						break;
 					}
@@ -2849,7 +2849,7 @@ class RandomTeams extends Dex.ModdedDex {
 		return {
 			name: setData.set.name || template.baseSpecies,
 			species: setData.set.species,
-			gender: setData.set.gender || template.gender || (this.random(2) ? 'M' : 'F'),
+			gender: setData.set.gender || template.gender || (!this.randomChance(1, 2) ? 'M' : 'F'),
 			item: setData.set.item || '',
 			ability: setData.set.ability || template.abilities['0'],
 			shiny: typeof setData.set.shiny === 'undefined' ? this.randomChance(1, 1024) : setData.set.shiny,
@@ -2903,7 +2903,7 @@ class RandomTeams extends Dex.ModdedDex {
 			let types = template.types;
 			let skip = false;
 			for (let t = 0; t < types.length; t++) {
-				if (teamData.typeCount[types[t]] > 1 && this.random(5)) {
+				if (teamData.typeCount[types[t]] > 1 && !this.randomChance(1, 5)) {
 					skip = true;
 					break;
 				}
@@ -3062,7 +3062,7 @@ class RandomTeams extends Dex.ModdedDex {
 		return {
 			name: setData.set.nickname || setData.set.name || template.baseSpecies,
 			species: setData.set.species,
-			gender: setData.set.gender || template.gender || (this.random(2) ? 'M' : 'F'),
+			gender: setData.set.gender || template.gender || (!this.randomChance(1, 2) ? 'M' : 'F'),
 			item: setData.set.item || '',
 			ability: setData.set.ability || template.abilities['0'],
 			shiny: typeof setData.set.shiny === 'undefined' ? this.randomChance(1, 1024) : setData.set.shiny,
@@ -3112,7 +3112,7 @@ class RandomTeams extends Dex.ModdedDex {
 			let types = template.types;
 			let skip = false;
 			for (let t = 0; t < types.length; t++) {
-				if (teamData.typeCount[types[t]] > 1 && this.random(5)) {
+				if (teamData.typeCount[types[t]] > 1 && !this.randomChance(1, 5)) {
 					skip = true;
 					break;
 				}
diff --git a/data/scripts.js b/data/scripts.js
index 417f0cbc67..81d44d5884 100644
--- a/data/scripts.js
+++ b/data/scripts.js
@@ -417,7 +417,7 @@ exports.BattleScripts = {
 		} else {
 			accuracy = this.runEvent('Accuracy', target, pokemon, move, accuracy);
 		}
-		if (accuracy !== true && this.random(100) >= accuracy) {
+		if (accuracy !== true && !this.randomChance(accuracy, 100)) {
 			if (!move.spreadHit) this.attrLastMove('[miss]');
 			this.add('-miss', pokemon, target);
 			return false;
@@ -516,7 +516,7 @@ exports.BattleScripts = {
 					accuracy = this.runEvent('ModifyAccuracy', target, pokemon, move, accuracy);
 					if (!move.alwaysHit) {
 						accuracy = this.runEvent('Accuracy', target, pokemon, move, accuracy);
-						if (accuracy !== true && this.random(100) >= accuracy) break;
+						if (accuracy !== true && !this.randomChance(accuracy, 100)) break;
 					}
 				}
 
diff --git a/data/statuses.js b/data/statuses.js
index f263354921..1fe41321a9 100644
--- a/data/statuses.js
+++ b/data/statuses.js
@@ -168,7 +168,7 @@ exports.BattleStatuses = {
 				return;
 			}
 			this.add('-activate', pokemon, 'confusion');
-			if (this.random(3) > 0) {
+			if (!this.randomChance(1, 3)) {
 				return;
 			}
 			this.activeTarget = pokemon;
@@ -404,7 +404,7 @@ exports.BattleStatuses = {
 			// However, just in case, use 1 if it is undefined.
 			let counter = this.effectData.counter || 1;
 			this.debug("Success chance: " + Math.round(100 / counter) + "%");
-			return (this.random(counter) === 0);
+			return this.randomChance(1, counter);
 		},
 		onRestart: function () {
 			if (this.effectData.counter < this.effect.counterMax) {
diff --git a/mods/gen1/random-teams.js b/mods/gen1/random-teams.js
index c4b6a3ebcf..256387583c 100644
--- a/mods/gen1/random-teams.js
+++ b/mods/gen1/random-teams.js
@@ -168,7 +168,7 @@ class RandomGen1Teams extends RandomGen2Teams {
 			// Limit 2 of any type as well. Diversity and minor weakness count.
 			// The second of a same type has halved chance of being added.
 			for (const type of template.types) {
-				if (typeCount[type] > 1 || (typeCount[type] === 1 && this.random(2) && pokemonPool.length > 1)) {
+				if (typeCount[type] > 1 || (typeCount[type] === 1 && !this.randomChance(1, 2) && pokemonPool.length > 1)) {
 					skip = true;
 					break;
 				}
diff --git a/mods/gen1/scripts.js b/mods/gen1/scripts.js
index 9d577b2ce9..5e8cee57d4 100644
--- a/mods/gen1/scripts.js
+++ b/mods/gen1/scripts.js
@@ -292,7 +292,7 @@ exports.BattleScripts = {
 		if (move.target === 'self' && accuracy !== true) accuracy++;
 
 		// 1/256 chance of missing always, no matter what. Besides the aforementioned exceptions.
-		if (accuracy !== true && this.random(256) >= accuracy) {
+		if (accuracy !== true && !this.randomChance(accuracy, 256)) {
 			this.attrLastMove('[miss]');
 			this.add('-miss', pokemon);
 			damage = false;
@@ -571,7 +571,7 @@ exports.BattleScripts = {
 				// If a move that was not fire-type would exist on Gen 1, it could burn a Pokémon.
 				if (!(secondary.status && ['par', 'brn', 'frz'].includes(secondary.status) && target && target.hasType(move.type))) {
 					let effectChance = Math.ceil(secondary.chance * 256 / 100);
-					if (typeof secondary.chance === 'undefined' || this.random(256) < effectChance) {
+					if (typeof secondary.chance === 'undefined' || this.randomChance(effectChance, 256)) {
 						this.moveHit(target, pokemon, move, secondary, true, isSelf);
 					}
 				}
@@ -832,7 +832,7 @@ exports.BattleScripts = {
 			// We compare our critical hit chance against a random number between 0 and 255.
 			// If the random number is lower, we get a critical hit. This means there is always a 1/255 chance of not hitting critically.
 			if (critChance > 0) {
-				move.crit = (this.random(256) < critChance);
+				move.crit = this.randomChance(critChance, 256);
 			}
 		}
 
diff --git a/mods/gen1/statuses.js b/mods/gen1/statuses.js
index f683022d7c..f92500714d 100644
--- a/mods/gen1/statuses.js
+++ b/mods/gen1/statuses.js
@@ -255,7 +255,7 @@ exports.BattleStatuses = {
 				return (this.random() * 4294967296 < 1);
 			}
 			this.debug("Success chance: " + Math.round(100 / counter) + "%");
-			return (this.random(counter) === 0);
+			return this.randomChance(1, counter);
 		},
 		onRestart: function () {
 			if (this.effectData.counter < this.effect.counterMax) {
diff --git a/mods/gen2/random-teams.js b/mods/gen2/random-teams.js
index c3861c7827..4a874301c2 100644
--- a/mods/gen2/random-teams.js
+++ b/mods/gen2/random-teams.js
@@ -56,7 +56,7 @@ class RandomGen2Teams extends RandomGen3Teams {
 				if (typeCount[types[0]] && this.randomChance(1, 3)) skip = true;
 			} else if (types.length === 2) {
 				if (typeCount[types[0]] > 1 || typeCount[types[1]] > 1) skip = true;
-				if (typeCount[types[0]] && typeCount[types[1]] && this.random(3) > 0) skip = true;
+				if (typeCount[types[0]] && typeCount[types[1]] && !this.randomChance(1, 3)) skip = true;
 			}
 
 			// Ensure the weakness-resistance balance is 2 points or lower for all types,
diff --git a/mods/gen2/scripts.js b/mods/gen2/scripts.js
index c22d1ed92d..990b766b22 100644
--- a/mods/gen2/scripts.js
+++ b/mods/gen2/scripts.js
@@ -197,7 +197,7 @@ exports.BattleScripts = {
 		} else {
 			accuracy = this.runEvent('Accuracy', target, pokemon, move, accuracy);
 		}
-		if (accuracy !== true && accuracy !== 255 && this.random(256) >= accuracy) {
+		if (accuracy !== true && accuracy !== 255 && !this.randomChance(accuracy, 256)) {
 			this.attrLastMove('[miss]');
 			this.add('-miss', pokemon);
 			damage = false;
@@ -400,7 +400,7 @@ exports.BattleScripts = {
 				// Unlike gen 1, though, paralysis works for all unless the target is immune to direct move (ie. ground-types and t-wave).
 				if (!(secondary.status && ['brn', 'frz'].includes(secondary.status) && target && target.hasType(move.type))) {
 					let effectChance = Math.floor(secondary.chance * 255 / 100);
-					if (typeof secondary.chance === 'undefined' || this.random(256) < effectChance) {
+					if (typeof secondary.chance === 'undefined' || this.randomChance(effectChance, 256)) {
 						this.moveHit(target, pokemon, move, secondary, true, isSelf);
 					}
 				}
@@ -485,7 +485,7 @@ exports.BattleScripts = {
 		move.crit = move.willCrit || false;
 		if (typeof move.willCrit === 'undefined') {
 			if (move.critRatio) {
-				move.crit = (this.random(critMult[move.critRatio]) === 0);
+				move.crit = this.randomChance(1, critMult[move.critRatio]);
 			}
 		}
 
diff --git a/mods/gen2/statuses.js b/mods/gen2/statuses.js
index 738c3d6431..f7de35fa05 100644
--- a/mods/gen2/statuses.js
+++ b/mods/gen2/statuses.js
@@ -183,7 +183,7 @@ exports.BattleStatuses = {
 		onStallMove: function () {
 			let counter = Math.floor(this.effectData.counter) || 127;
 			this.debug("Success chance: " + Math.round(counter * 1000 / 255) / 10 + "% (" + counter + "/255)");
-			return (this.random(255) < counter);
+			return this.randomChance(counter, 255);
 		},
 		onRestart: function () {
 			this.effectData.counter /= 2;
diff --git a/mods/gen3/random-teams.js b/mods/gen3/random-teams.js
index 5eb301d0cd..91bad632d9 100644
--- a/mods/gen3/random-teams.js
+++ b/mods/gen3/random-teams.js
@@ -430,7 +430,7 @@ class RandomGen3Teams extends RandomGen4Teams {
 		if (ability0.gen !== 3) ability = ability1.name;
 		if (ability0.gen === 3 && ability1.gen === 3) {
 			if (ability0.rating <= ability1.rating) {
-				if (this.random(2)) ability = ability1.name;
+				if (!this.randomChance(1, 2)) ability = ability1.name;
 			} else if (ability0.rating - 0.6 <= ability1.rating) {
 				if (this.randomChance(1, 3)) ability = ability1.name;
 			}
@@ -512,15 +512,15 @@ class RandomGen3Teams extends RandomGen4Teams {
 		} else if (hasMove['leechseed']) {
 			item = 'Leftovers';
 		} else if (hasMove['endeavor'] || hasMove['flail'] || hasMove['reversal'] || hasMove['endure'] ||
-			hasMove['substitute'] && counter.Status < 3 && template.baseStats.hp + template.baseStats.def + template.baseStats.spd < 250 && this.random(2)) {
+			hasMove['substitute'] && counter.Status < 3 && template.baseStats.hp + template.baseStats.def + template.baseStats.spd < 250 && !this.randomChance(1, 2)) {
 			if (template.baseStats.spe <= 90 && !counter['speedsetup'] && !hasMove['focuspunch']) {
 				item = 'Salac Berry';
-			} else if (counter.Physical > counter.Special || counter.Physical === counter.Special && this.random(2)) {
+			} else if (counter.Physical > counter.Special || counter.Physical === counter.Special && !this.randomChance(1, 2)) {
 				item = 'Liechi Berry';
 			} else {
 				item = 'Petaya Berry';
 			}
-		} else if ((counter.Physical >= 4 || counter.Physical >= 3 && counter.Special === 1 && this.random(2)) && !(hasMove['bodyslam'] && hasAbility['Serene Grace']) && !hasMove['fakeout'] && !hasMove['rapidspin']) {
+		} else if ((counter.Physical >= 4 || counter.Physical >= 3 && counter.Special === 1 && !this.randomChance(1, 2)) && !(hasMove['bodyslam'] && hasAbility['Serene Grace']) && !hasMove['fakeout'] && !hasMove['rapidspin']) {
 			item = 'Choice Band';
 		} else if (hasMove['curse'] || hasMove['protect'] || hasMove['sleeptalk'] || hasMove['substitute']) {
 			item = 'Leftovers';
diff --git a/mods/gen4/random-teams.js b/mods/gen4/random-teams.js
index 89bdf82544..75ad5f644e 100644
--- a/mods/gen4/random-teams.js
+++ b/mods/gen4/random-teams.js
@@ -450,7 +450,7 @@ class RandomGen4Teams extends RandomGen5Teams {
 		ability = ability0.name;
 		if (abilities[1]) {
 			if (ability0.rating <= ability1.rating) {
-				if (this.random(2)) ability = ability1.name;
+				if (!this.randomChance(1, 2)) ability = ability1.name;
 			} else if (ability0.rating - 0.6 <= ability1.rating) {
 				if (this.randomChance(1, 3)) ability = ability1.name;
 			}
@@ -539,7 +539,7 @@ class RandomGen4Teams extends RandomGen5Teams {
 		} else if (template.species === 'Wobbuffet') {
 			item = hasMove['destinybond'] ? 'Custap Berry' : ['Leftovers', 'Sitrus Berry'][this.random(2)];
 		} else if (hasMove['switcheroo'] || hasMove['trick']) {
-			let randomNum = this.random(3);
+			let randomNum = !this.randomChance(1, 3);
 			if (counter.Physical >= 3 && (template.baseStats.spe < 60 || template.baseStats.spe > 108 || randomNum)) {
 				item = 'Choice Band';
 			} else if (counter.Special >= 3 && (template.baseStats.spe < 60 || template.baseStats.spe > 108 || randomNum)) {
@@ -568,9 +568,9 @@ class RandomGen4Teams extends RandomGen5Teams {
 
 		// Medium priority
 		} else if (counter.Physical >= 4 && !(hasMove['bodyslam'] && hasAbility['Serene Grace']) && !hasMove['fakeout'] && !hasMove['rapidspin'] && !hasMove['suckerpunch']) {
-			item = template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !hasMove['bodyslam'] && this.random(3) ? 'Choice Scarf' : 'Choice Band';
+			item = template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !hasMove['bodyslam'] && !this.randomChance(1, 3) ? 'Choice Scarf' : 'Choice Band';
 		} else if ((counter.Special >= 4 || (counter.Special >= 3 && (hasMove['batonpass'] || hasMove['uturn'] || hasMove['waterspout'] && hasMove['selfdestruct']))) && !hasMove['chargebeam']) {
-			item = template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && ability !== 'Speed Boost' && !counter['priority'] && this.random(3) ? 'Choice Scarf' : 'Choice Specs';
+			item = template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && ability !== 'Speed Boost' && !counter['priority'] && !this.randomChance(1, 3) ? 'Choice Scarf' : 'Choice Specs';
 		} else if (hasMove['endeavor'] || hasMove['flail'] || hasMove['reversal']) {
 			item = 'Focus Sash';
 		} else if (ability === 'Slow Start' || hasMove['curse'] || hasMove['detect'] || hasMove['leechseed'] || hasMove['protect'] || hasMove['roar'] || hasMove['sleeptalk'] || hasMove['whirlwind']) {
diff --git a/mods/gen5/random-teams.js b/mods/gen5/random-teams.js
index 744b35bd8f..1255392ae6 100644
--- a/mods/gen5/random-teams.js
+++ b/mods/gen5/random-teams.js
@@ -371,12 +371,12 @@ class RandomGen5Teams extends RandomGen6Teams {
 		let ability1 = this.getAbility(abilities[1]);
 		let ability2 = this.getAbility(abilities[2]);
 		if (abilities[1]) {
-			if (abilities[2] && ability1.rating <= ability2.rating && this.random(2)) {
+			if (abilities[2] && ability1.rating <= ability2.rating && !this.randomChance(1, 2)) {
 				[ability1, ability2] = [ability2, ability1];
 			}
-			if (ability0.rating <= ability1.rating && this.random(2)) {
+			if (ability0.rating <= ability1.rating && !this.randomChance(1, 2)) {
 				[ability0, ability1] = [ability1, ability0];
-			} else if (ability0.rating - 0.6 <= ability1.rating && this.random(3)) {
+			} else if (ability0.rating - 0.6 <= ability1.rating && !this.randomChance(1, 3)) {
 				[ability0, ability1] = [ability1, ability0];
 			}
 			ability = ability0.name;
@@ -472,7 +472,7 @@ class RandomGen5Teams extends RandomGen6Teams {
 			item = 'Focus Sash';
 		} else if (template.species === 'Unown') {
 			item = 'Choice Specs';
-		} else if (template.species === 'Wobbuffet' && hasMove['destinybond'] && this.random(2)) {
+		} else if (template.species === 'Wobbuffet' && hasMove['destinybond'] && !this.randomChance(1, 2)) {
 			item = 'Custap Berry';
 		} else if (ability === 'Imposter') {
 			item = 'Choice Scarf';
@@ -481,7 +481,7 @@ class RandomGen5Teams extends RandomGen6Teams {
 		} else if (hasMove['trick'] && hasMove['gyroball']) {
 			item = 'Iron Ball';
 		} else if (hasMove['switcheroo'] || hasMove['trick']) {
-			let randomNum = this.random(2);
+			let randomNum = !this.randomChance(1, 2);
 			if (counter.Physical >= 3 && (template.baseStats.spe >= 95 || randomNum)) {
 				item = 'Choice Band';
 			} else if (counter.Special >= 3 && (template.baseStats.spe >= 95 || randomNum)) {
@@ -531,9 +531,9 @@ class RandomGen5Teams extends RandomGen6Teams {
 		} else if (hasMove['lightscreen'] || hasMove['reflect']) {
 			item = 'Light Clay';
 		} else if (counter.Physical >= 4 && !hasMove['fakeout'] && !hasMove['suckerpunch'] && !hasMove['flamecharge'] && !hasMove['rapidspin']) {
-			item = this.random(3) ? 'Choice Band' : 'Expert Belt';
+			item = !this.randomChance(1, 3) ? 'Choice Band' : 'Expert Belt';
 		} else if (counter.Special >= 4) {
-			item = this.random(3) ? 'Choice Specs' : 'Expert Belt';
+			item = !this.randomChance(1, 3) ? 'Choice Specs' : 'Expert Belt';
 		} else if (this.getEffectiveness('Ground', template) >= 2 && ability !== 'Levitate' && !hasMove['magnetrise']) {
 			item = 'Air Balloon';
 		} else if ((hasMove['eruption'] || hasMove['waterspout']) && !counter['Status']) {
diff --git a/mods/gen5/statuses.js b/mods/gen5/statuses.js
index 01c4297175..d14fb7de4c 100644
--- a/mods/gen5/statuses.js
+++ b/mods/gen5/statuses.js
@@ -37,7 +37,7 @@ exports.BattleStatuses = {
 				return (this.random() * 4294967296 < 1);
 			}
 			this.debug("Success chance: " + Math.round(100 / counter) + "%");
-			return (this.random(counter) === 0);
+			return this.randomChance(1, counter);
 		},
 		onRestart: function () {
 			if (this.effectData.counter < this.effect.counterMax) {
diff --git a/mods/gen6/random-teams.js b/mods/gen6/random-teams.js
index 30e5b894e6..13c7cb407c 100644
--- a/mods/gen6/random-teams.js
+++ b/mods/gen6/random-teams.js
@@ -23,7 +23,7 @@ class RandomGen6Teams extends RandomTeams {
 			species = template.baseSpecies;
 		}
 		let battleForme = this.checkBattleForme(template);
-		if (battleForme && battleForme.tier !== 'AG' && (battleForme.isMega ? !teamDetails.megaStone : this.random(2))) {
+		if (battleForme && battleForme.tier !== 'AG' && (battleForme.isMega ? !teamDetails.megaStone : !this.randomChance(1, 2))) {
 			template = this.getTemplate(template.otherFormes.length >= 2 ? template.otherFormes[this.random(template.otherFormes.length)] : template.otherFormes[0]);
 		}
 
@@ -604,12 +604,12 @@ class RandomGen6Teams extends RandomTeams {
 		let ability1 = this.getAbility(abilities[1]);
 		let ability2 = this.getAbility(abilities[2]);
 		if (abilities[1]) {
-			if (abilities[2] && ability1.rating <= ability2.rating && this.random(2)) {
+			if (abilities[2] && ability1.rating <= ability2.rating && !this.randomChance(1, 2)) {
 				[ability1, ability2] = [ability2, ability1];
 			}
-			if (ability0.rating <= ability1.rating && this.random(2)) {
+			if (ability0.rating <= ability1.rating && !this.randomChance(1, 2)) {
 				[ability0, ability1] = [ability1, ability0];
-			} else if (ability0.rating - 0.6 <= ability1.rating && this.random(3)) {
+			} else if (ability0.rating - 0.6 <= ability1.rating && !this.randomChance(1, 3)) {
 				[ability0, ability1] = [ability1, ability0];
 			}
 			ability = ability0.name;
@@ -716,7 +716,7 @@ class RandomGen6Teams extends RandomTeams {
 				ability = 'Pickup';
 			} else if (template.baseSpecies === 'Basculin') {
 				ability = 'Adaptability';
-			} else if (template.species === 'Lopunny' && hasMove['switcheroo'] && this.random(3)) {
+			} else if (template.species === 'Lopunny' && hasMove['switcheroo'] && !this.randomChance(1, 3)) {
 				ability = 'Klutz';
 			} else if ((template.species === 'Rampardos' && !hasMove['headsmash']) || hasMove['rockclimb']) {
 				ability = 'Sheer Force';
@@ -758,7 +758,7 @@ class RandomGen6Teams extends RandomTeams {
 			// To perma-taunt a Pokemon by giving it Assault Vest
 			item = 'Assault Vest';
 		} else if (hasMove['switcheroo'] || hasMove['trick']) {
-			let randomNum = this.random(3);
+			let randomNum = !this.randomChance(1, 3);
 			if (counter.Physical >= 3 && (template.baseStats.spe < 60 || template.baseStats.spe > 108 || randomNum)) {
 				item = 'Choice Band';
 			} else if (counter.Special >= 3 && (template.baseStats.spe < 60 || template.baseStats.spe > 108 || randomNum)) {
@@ -814,10 +814,10 @@ class RandomGen6Teams extends RandomTeams {
 		} else if (((ability === 'Speed Boost' && !hasMove['substitute']) || (ability === 'Stance Change')) && counter.Physical + counter.Special > 2) {
 			item = 'Life Orb';
 		} else if (counter.Physical >= 4 && !hasMove['bodyslam'] && !hasMove['dragontail'] && !hasMove['fakeout'] && !hasMove['flamecharge'] && !hasMove['rapidspin'] && !hasMove['suckerpunch']) {
-			item = template.baseStats.atk >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && this.random(3) ? 'Choice Scarf' : 'Choice Band';
+			item = template.baseStats.atk >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !this.randomChance(1, 3) ? 'Choice Scarf' : 'Choice Band';
 		} else if (counter.Special >= 4 && !hasMove['acidspray'] && !hasMove['chargebeam'] && !hasMove['clearsmog'] && !hasMove['fierydance']) {
-			item = template.baseStats.spa >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && this.random(3) ? 'Choice Scarf' : 'Choice Specs';
-		} else if (((counter.Physical >= 3 && hasMove['defog']) || (counter.Special >= 3 && hasMove['uturn'])) && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && this.random(3)) {
+			item = template.baseStats.spa >= 100 && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !this.randomChance(1, 3) ? 'Choice Scarf' : 'Choice Specs';
+		} else if (((counter.Physical >= 3 && hasMove['defog']) || (counter.Special >= 3 && hasMove['uturn'])) && template.baseStats.spe >= 60 && template.baseStats.spe <= 108 && !counter['priority'] && !this.randomChance(1, 3)) {
 			item = 'Choice Scarf';
 		} else if (ability === 'Defeatist' || hasMove['eruption'] || hasMove['waterspout']) {
 			item = counter.Status <= 1 ? 'Expert Belt' : 'Leftovers';
@@ -831,7 +831,7 @@ class RandomGen6Teams extends RandomTeams {
 			item = 'Leftovers';
 		} else if (hasMove['substitute']) {
 			item = !counter['drain'] || counter.damagingMoves.length < 2 ? 'Leftovers' : 'Life Orb';
-		} else if ((ability === 'Iron Barbs' || ability === 'Rough Skin') && this.random(2)) {
+		} else if ((ability === 'Iron Barbs' || ability === 'Rough Skin') && !this.randomChance(1, 2)) {
 			item = 'Rocky Helmet';
 		} else if (counter.Physical + counter.Special >= 4 && template.baseStats.spd >= 65 && template.baseStats.hp + template.baseStats.def + template.baseStats.spd >= 235) {
 			item = 'Assault Vest';
diff --git a/mods/stadium/scripts.js b/mods/stadium/scripts.js
index 1a12103d16..694e7736b5 100644
--- a/mods/stadium/scripts.js
+++ b/mods/stadium/scripts.js
@@ -172,7 +172,7 @@ exports.BattleScripts = {
 		accuracy = this.runEvent('Accuracy', target, pokemon, move, accuracy);
 
 		// Stadium fixes the 1/256 accuracy bug.
-		if (accuracy !== true && this.random(256) > accuracy) {
+		if (accuracy !== true && !this.randomChance(accuracy + 1, 256)) {
 			this.attrLastMove('[miss]');
 			this.add('-miss', pokemon);
 			damage = false;
@@ -389,7 +389,7 @@ exports.BattleScripts = {
 				// If a move that was not fire-type would exist on Gen 1, it could burn a Pokémon.
 				if (!(secondary.status && ['par', 'brn', 'frz'].includes(secondary.status) && target && target.hasType(move.type))) {
 					let effectChance = Math.floor(secondary.chance * 255 / 100);
-					if (typeof secondary.chance === 'undefined' || this.random(256) <= effectChance) {
+					if (typeof secondary.chance === 'undefined' || this.randomChance(effectChance + 1, 256)) {
 						this.moveHit(target, pokemon, move, secondary, true, isSelf);
 					}
 				}
@@ -508,7 +508,7 @@ exports.BattleScripts = {
 			// We compare our critical hit chance against a random number between 0 and 255.
 			// If the random number is lower, we get a critical hit. This means there is always a 1/255 chance of not hitting critically.
 			if (critChance > 0) {
-				move.crit = (this.random(256) < critChance);
+				move.crit = this.randomChance(critChance, 256);
 			}
 		}
 		// There is a critical hit.
diff --git a/sim/battle.js b/sim/battle.js
index 3630ce556e..1803244838 100644
--- a/sim/battle.js
+++ b/sim/battle.js
@@ -2211,7 +2211,7 @@ class Battle extends Dex.ModdedDex {
 		move.crit = move.willCrit || false;
 		if (move.willCrit === undefined) {
 			if (critRatio) {
-				move.crit = (this.random(critMult[critRatio]) === 0);
+				move.crit = this.randomChance(1, critMult[critRatio]);
 			}
 		}