diff --git a/sim/dex-formats.ts b/sim/dex-formats.ts
index 74cf990c48..ff9e2f420b 100644
--- a/sim/dex-formats.ts
+++ b/sim/dex-formats.ts
@@ -97,6 +97,11 @@ export class RuleTable extends Map<string, string> {
 		return this.has(`*pokemontag:allpokemon`);
 	}
 
+	/**
+	 * - non-empty string: banned, string is the reason
+	 * - '': whitelisted
+	 * - null: neither whitelisted nor banned
+	 */
 	check(thing: string, setHas: {[id: string]: true} | null = null) {
 		if (this.has(`+${thing}`)) return '';
 		if (setHas) setHas[thing] = true;
@@ -619,8 +624,6 @@ export class DexFormats {
 
 	getTagRules(ruleTable: RuleTable) {
 		const tagRules = [];
-		const specificExistenceTagRules = [];
-		const existenceTagRules = [];
 		for (const ruleid of ruleTable.keys()) {
 			if (/^[+*-]pokemontag:/.test(ruleid)) {
 				const banid = ruleid.slice(12);
@@ -629,25 +632,14 @@ export class DexFormats {
 					banid === 'allabilities' || banid === 'allnatures'
 				) {
 					// hardcoded and not a part of the ban rule system
-				} else if (!ruleid.startsWith('+') && (
-					banid === 'past' || banid === 'future' || banid === 'lgpe' ||
-					banid === 'unobtainable' || banid === 'cap' || banid === 'custom'
-				)) {
-					specificExistenceTagRules.push(ruleid);
-				} else if (!ruleid.startsWith('+') && banid === 'nonexistent') {
-					existenceTagRules.push(ruleid);
 				} else {
 					tagRules.push(ruleid);
 				}
 			} else if ('+*-'.includes(ruleid.charAt(0)) && ruleid.slice(1) === 'nonexistent') {
-				if (!ruleid.startsWith('+')) {
-					existenceTagRules.push(ruleid.charAt(0) + 'pokemontag:nonexistent');
-				} else {
-					tagRules.push('+pokemontag:nonexistent');
-				}
+				tagRules.push(ruleid.charAt(0) + 'pokemontag:nonexistent');
 			}
 		}
-		ruleTable.tagRules = [...tagRules, ...existenceTagRules, ...specificExistenceTagRules].reverse();
+		ruleTable.tagRules = tagRules.reverse();
 	}
 
 	validateRule(rule: string, format: Format | null = null) {
diff --git a/sim/team-validator.ts b/sim/team-validator.ts
index d64de8bd88..d987d04196 100644
--- a/sim/team-validator.ts
+++ b/sim/team-validator.ts
@@ -1334,15 +1334,25 @@ export class TeamValidator {
 			}
 		}
 
+		// We can't return here because the `-nonexistent` rule is a bit
+		// complicated in terms of what trumps it. We don't want e.g.
+		// +Mythical to unban Shaymin in Gen 1, for instance.
+		const nonexistentCheck = Tags.nonexistent.genericFilter!(tierSpecies) && ruleTable.check('nonexistent');
+
 		const EXISTENCE_TAG = ['past', 'future', 'lgpe', 'unobtainable', 'cap', 'custom', 'nonexistent'];
-		console.log(ruleTable.tagRules);
+
 		for (const ruleid of ruleTable.tagRules) {
 			if (ruleid.startsWith('*')) continue;
 			const tagid = ruleid.slice(12);
 			const tag = Tags[tagid];
 			if ((tag.speciesFilter || tag.genericFilter)!(tierSpecies)) {
-				if (ruleid.startsWith('+')) return null;
-				if (EXISTENCE_TAG.includes(tagid)) {
+				const existenceTag = EXISTENCE_TAG.includes(tagid);
+				if (ruleid.startsWith('+')) {
+					// we want rules like +CAP to trump -Nonexistent, but most tags shouldn't
+					if (!existenceTag && nonexistentCheck) continue;
+					return null;
+				}
+				if (existenceTag) {
 					if (tierSpecies.isNonstandard === 'Past' || tierSpecies.isNonstandard === 'Future') {
 						return `${tierSpecies.name} does not exist in Gen ${dex.gen}.`;
 					}
@@ -1363,6 +1373,11 @@ export class TeamValidator {
 			}
 		}
 
+		if (nonexistentCheck) {
+			return `Despite being whitelisted by a tag, ${tierSpecies.name} does not exist in this game.`;
+		}
+		if (nonexistentCheck === '') return null;
+
 		// Special casing for Pokemon that can Gmax, but their Gmax factor cannot be legally obtained
 		if (tierSpecies.gmaxUnreleased && set.gigantamax) {
 			banReason = ruleTable.check('pokemontag:unobtainable');
diff --git a/test/sim/team-validator.js b/test/sim/team-validator.js
index c8f3dfb19f..cf10f6833a 100644
--- a/test/sim/team-validator.js
+++ b/test/sim/team-validator.js
@@ -767,16 +767,22 @@ describe('Team Validator', function () {
 
 	it('should support banning/unbanning tag combinations', function () {
 		let team = [
-			{species: 'Blaziken-Mega', ability: 'Speed Boost', moves: ['protect'], evs: {hp: 1}},
+			{species: 'Crucibelle-Mega', ability: 'Regenerator', moves: ['protect'], evs: {hp: 1}},
 		];
 		let illegal = TeamValidator.get('gen8customgame@@@-nonexistent,+mega').validateTeam(team);
 		assert(illegal, "Nonexistent should override all tags that aren't existence-related");
 
 		team = [
-			{species: 'Blaziken-Mega', ability: 'Speed Boost', moves: ['protect'], evs: {hp: 1}},
+			{species: 'Crucibelle-Mega', ability: 'Regenerator', moves: ['protect'], evs: {hp: 1}},
 		];
 		illegal = TeamValidator.get('gen8customgame@@@+mega,-nonexistent').validateTeam(team);
 		assert(illegal, "Nonexistent should override all tags that aren't existence-related");
+
+		team = [
+			{species: 'Crucibelle-Mega', ability: 'Regenerator', moves: ['protect'], evs: {hp: 1}},
+		];
+		illegal = TeamValidator.get('gen8customgame@@@-nonexistent,+crucibellemega').validateTeam(team);
+		assert.equal(illegal, null, "Nonexistent should override all tags that aren't existence-related");
 	});
 
 	it('should allow moves to be banned', function () {