diff --git a/data/mods/gen1/moves.ts b/data/mods/gen1/moves.ts
index 9bb9510f3f..11f8d8f6e9 100644
--- a/data/mods/gen1/moves.ts
+++ b/data/mods/gen1/moves.ts
@@ -482,9 +482,8 @@ export const Moves: import('../../../sim/dex-moves').ModdedMoveDataTable = {
 		inherit: true,
 		onHit(pokemon) {
 			const foe = pokemon.side.foe.active[0];
-			if (!foe?.lastMove || foe.lastMove.id === 'mirrormove') {
-				return false;
-			}
+			// only Mirror Move isn't mirrorable
+			if (!foe?.lastMove?.flags['mirror']) return false;
 			pokemon.side.lastSelectedMove = foe.lastMove.id;
 			this.actions.useMove(foe.lastMove.id, pokemon);
 		},
diff --git a/data/mods/gen1/scripts.ts b/data/mods/gen1/scripts.ts
index 83812bfa95..6e9cc33f16 100644
--- a/data/mods/gen1/scripts.ts
+++ b/data/mods/gen1/scripts.ts
@@ -21,6 +21,16 @@ export const Scripts: ModdedBattleScriptsData = {
 			poke.gender = 'N';
 			poke.eggGroups = null;
 		}
+		for (const i in this.data.Moves) {
+			const move = this.data.Moves[i];
+			if (i === 'mirrormove') {
+				const flags = { ...move.flags };
+				delete flags['mirror'];
+				this.modData('Moves', i).flags = flags;
+			} else {
+				this.modData('Moves', i).flags = { mirror: 1, ...move.flags };
+			}
+		}
 	},
 	// BattlePokemon scripts.
 	pokemon: {
diff --git a/data/mods/gen2/moves.ts b/data/mods/gen2/moves.ts
index c75e5a214f..2f5ccd8892 100644
--- a/data/mods/gen2/moves.ts
+++ b/data/mods/gen2/moves.ts
@@ -343,13 +343,10 @@ export const Moves: import('../../../sim/dex-moves').ModdedMoveDataTable = {
 		inherit: true,
 		flags: { metronome: 1, failencore: 1, nosketch: 1 },
 		onHit(pokemon) {
-			const noMirror = ['metronome', 'mimic', 'mirrormove', 'sketch', 'sleeptalk', 'transform'];
 			const target = pokemon.side.foe.active[0];
-			const lastMove = target?.lastMove && target?.lastMove.id;
-			if (!lastMove || (!pokemon.activeTurns && !target.moveThisTurn)) {
-				return false;
-			}
-			if (noMirror.includes(lastMove) || pokemon.moves.includes(lastMove)) {
+			const lastMove = target?.lastMove;
+			if (!lastMove?.flags['mirror'] || pokemon.moves.includes(lastMove.id) ||
+				(!pokemon.activeTurns && !target.moveThisTurn)) {
 				return false;
 			}
 			this.actions.useMove(lastMove, pokemon);
diff --git a/data/mods/gen2/scripts.ts b/data/mods/gen2/scripts.ts
index 5bb79245ba..c66fef1c0d 100644
--- a/data/mods/gen2/scripts.ts
+++ b/data/mods/gen2/scripts.ts
@@ -5,6 +5,19 @@
 export const Scripts: ModdedBattleScriptsData = {
 	inherit: 'gen3',
 	gen: 2,
+	init() {
+		const noMirror = ['metronome', 'mimic', 'mirrormove', 'sketch', 'sleeptalk', 'transform'];
+		for (const i in this.data.Moves) {
+			const move = this.data.Moves[i];
+			if (noMirror.includes(i)) {
+				const flags = { ...move.flags };
+				delete flags['mirror'];
+				this.modData('Moves', i).flags = flags;
+			} else {
+				this.modData('Moves', i).flags = { mirror: 1, ...move.flags };
+			}
+		}
+	},
 	pokemon: {
 		inherit: true,
 		getStat(statName, unboosted, unmodified, fastReturn) {
diff --git a/data/mods/gen3/moves.ts b/data/mods/gen3/moves.ts
index 06cdde7a04..99f0667882 100644
--- a/data/mods/gen3/moves.ts
+++ b/data/mods/gen3/moves.ts
@@ -428,21 +428,6 @@ export const Moves: import('../../../sim/dex-moves').ModdedMoveDataTable = {
 	mirrormove: {
 		inherit: true,
 		flags: { metronome: 1, failencore: 1, nosleeptalk: 1, noassist: 1 },
-		onTryHit: undefined, // no inherit
-		onHit(pokemon) {
-			const noMirror = [
-				'assist', 'curse', 'doomdesire', 'focuspunch', 'futuresight', 'magiccoat', 'metronome', 'mimic', 'mirrormove', 'naturepower', 'psychup', 'roleplay', 'sketch', 'sleeptalk', 'spikes', 'spitup', 'taunt', 'teeterdance', 'transform',
-			];
-			const lastAttackedBy = pokemon.getLastAttackedBy();
-			if (!lastAttackedBy?.source.lastMove || !lastAttackedBy.move) {
-				return false;
-			}
-			if (noMirror.includes(lastAttackedBy.move) || !lastAttackedBy.source.hasMove(lastAttackedBy.move)) {
-				return false;
-			}
-			this.actions.useMove(lastAttackedBy.move, pokemon);
-		},
-		target: "self",
 	},
 	naturepower: {
 		inherit: true,
diff --git a/data/mods/gen3/scripts.ts b/data/mods/gen3/scripts.ts
index 75d9dd50ee..f7c6c5c4bd 100644
--- a/data/mods/gen3/scripts.ts
+++ b/data/mods/gen3/scripts.ts
@@ -3,14 +3,25 @@ export const Scripts: ModdedBattleScriptsData = {
 	gen: 3,
 	init() {
 		const specialTypes = ['Fire', 'Water', 'Grass', 'Ice', 'Electric', 'Dark', 'Psychic', 'Dragon'];
+		const noMirror = [
+			'assist', 'curse', 'doomdesire', 'focuspunch', 'futuresight', 'magiccoat', 'metronome', 'mimic', 'mirrormove', 'naturepower', 'psychup', 'roleplay', 'sketch', 'sleeptalk', 'spikes', 'spitup', 'taunt', 'teeterdance', 'transform',
+		];
 		let newCategory = '';
 		for (const i in this.data.Moves) {
-			if (!this.data.Moves[i]) console.log(i);
-			if (this.data.Moves[i].category === 'Status') continue;
-			newCategory = specialTypes.includes(this.data.Moves[i].type) ? 'Special' : 'Physical';
-			if (newCategory !== this.data.Moves[i].category) {
+			const move = this.data.Moves[i];
+			if (!move) console.log(i);
+			if (move.category === 'Status') continue;
+			newCategory = specialTypes.includes(move.type) ? 'Special' : 'Physical';
+			if (newCategory !== move.category) {
 				this.modData('Moves', i).category = newCategory;
 			}
+			if (noMirror.includes(i)) {
+				const flags = { ...move.flags };
+				delete flags['mirror'];
+				this.modData('Moves', i).flags = flags;
+			} else {
+				this.modData('Moves', i).flags = { mirror: 1, ...move.flags };
+			}
 		}
 	},
 	pokemon: {
diff --git a/data/mods/gen4/moves.ts b/data/mods/gen4/moves.ts
index 795aa6e7c8..0d8259149b 100644
--- a/data/mods/gen4/moves.ts
+++ b/data/mods/gen4/moves.ts
@@ -895,13 +895,11 @@ export const Moves: import('../../../sim/dex-moves').ModdedMoveDataTable = {
 			if (!lastAttackedBy?.source.lastMove || !lastAttackedBy.move) {
 				return false;
 			}
-			const noMirror = [
-				'acupressure', 'aromatherapy', 'assist', 'chatter', 'copycat', 'counter', 'curse', 'doomdesire', 'feint', 'focuspunch', 'futuresight', 'gravity', 'hail', 'haze', 'healbell', 'helpinghand', 'lightscreen', 'luckychant', 'magiccoat', 'mefirst', 'metronome', 'mimic', 'mirrorcoat', 'mirrormove', 'mist', 'mudsport', 'naturepower', 'perishsong', 'psychup', 'raindance', 'reflect', 'roleplay', 'safeguard', 'sandstorm', 'sketch', 'sleeptalk', 'snatch', 'spikes', 'spitup', 'stealthrock', 'struggle', 'sunnyday', 'tailwind', 'toxicspikes', 'transform', 'watersport',
-			];
-			if (noMirror.includes(lastAttackedBy.move) || !lastAttackedBy.source.hasMove(lastAttackedBy.move)) {
+			const move = this.dex.moves.get(lastAttackedBy.move);
+			if (!move.flags['mirror'] || !lastAttackedBy.source.hasMove(move.id)) {
 				return false;
 			}
-			this.actions.useMove(lastAttackedBy.move, pokemon);
+			this.actions.useMove(move, pokemon);
 		},
 		target: "self",
 	},
diff --git a/data/mods/gen4/scripts.ts b/data/mods/gen4/scripts.ts
index c28929177d..002f91955a 100644
--- a/data/mods/gen4/scripts.ts
+++ b/data/mods/gen4/scripts.ts
@@ -1,6 +1,21 @@
 export const Scripts: ModdedBattleScriptsData = {
 	inherit: 'gen5',
 	gen: 4,
+	init() {
+		const noMirror = [
+			'acupressure', 'aromatherapy', 'assist', 'chatter', 'copycat', 'counter', 'curse', 'doomdesire', 'feint', 'focuspunch', 'futuresight', 'gravity', 'hail', 'haze', 'healbell', 'helpinghand', 'lightscreen', 'luckychant', 'magiccoat', 'mefirst', 'metronome', 'mimic', 'mirrorcoat', 'mirrormove', 'mist', 'mudsport', 'naturepower', 'perishsong', 'psychup', 'raindance', 'reflect', 'roleplay', 'safeguard', 'sandstorm', 'sketch', 'sleeptalk', 'snatch', 'spikes', 'spitup', 'stealthrock', 'struggle', 'sunnyday', 'tailwind', 'toxicspikes', 'transform', 'watersport',
+		];
+		for (const i in this.data.Moves) {
+			const move = this.data.Moves[i];
+			if (noMirror.includes(i)) {
+				const flags = { ...move.flags };
+				delete flags['mirror'];
+				this.modData('Moves', i).flags = flags;
+			} else {
+				this.modData('Moves', i).flags = { mirror: 1, ...move.flags };
+			}
+		}
+	},
 	pokemon: {
 		inherit: true,
 		getActionSpeed() {
diff --git a/sim/dex-species.ts b/sim/dex-species.ts
index 688891f42b..c066675eba 100644
--- a/sim/dex-species.ts
+++ b/sim/dex-species.ts
@@ -594,11 +594,12 @@ export class DexSpecies {
 			species.canHatch = species.canHatch ||
 				(!['Ditto', 'Undiscovered'].includes(species.eggGroups[0]) && !species.prevo && species.name !== 'Manaphy');
 			if (this.dex.gen === 1) species.bst -= species.baseStats.spd;
-			if (this.dex.gen < 5) {
+			if (this.dex.gen <= 2) species.abilities = { 0: 'No Ability' };
+			else if (this.dex.gen < 5) {
 				species.abilities = this.dex.deepClone(species.abilities);
 				delete species.abilities['H'];
+				if (this.dex.gen === 3 && this.dex.abilities.get(species.abilities['1']).gen === 4) delete species.abilities['1'];
 			}
-			if (this.dex.gen === 3 && this.dex.abilities.get(species.abilities['1']).gen === 4) delete species.abilities['1'];
 
 			if (this.dex.parentMod) {
 				// if this species is exactly identical to parentMod's species, reuse parentMod's copy