diff --git a/play.pokemonshowdown.com/js/client-teambuilder.js b/play.pokemonshowdown.com/js/client-teambuilder.js
index 8d8c4d809d..5a265b5b3b 100644
--- a/play.pokemonshowdown.com/js/client-teambuilder.js
+++ b/play.pokemonshowdown.com/js/client-teambuilder.js
@@ -1521,8 +1521,8 @@
 					}
 					if (this.curTeam.gen >= 6) {
 						var item = dex.items.get(set.item);
-						if (item.megaStone && species.baseSpecies === item.megaEvolves) {
-							species = dex.species.get(item.megaStone);
+						if (item.megaEvolves && item.megaEvolves[species.baseSpecies]) {
+							species = dex.species.get(item.megaEvolves[species.baseSpecies]);
 							typeTable = typeTable.filter(function (type) {
 								return species.types.includes(type);
 							});
diff --git a/play.pokemonshowdown.com/src/battle-dex-data.ts b/play.pokemonshowdown.com/src/battle-dex-data.ts
index 983da372f6..df2ec834d2 100644
--- a/play.pokemonshowdown.com/src/battle-dex-data.ts
+++ b/play.pokemonshowdown.com/src/battle-dex-data.ts
@@ -1154,8 +1154,7 @@ export class Item implements Effect {
 	readonly desc: string;
 	readonly shortDesc: string;
 
-	readonly megaStone: string;
-	readonly megaEvolves: string;
+	readonly megaStone: { [megaEvolves: string]: string };
 	readonly zMove: string | true | null;
 	readonly zMoveType: TypeName | '';
 	readonly zMoveFrom: string;
@@ -1181,8 +1180,7 @@ export class Item implements Effect {
 		this.desc = data.desc || data.shortDesc || '';
 		this.shortDesc = data.shortDesc || this.desc;
 
-		this.megaStone = data.megaStone || '';
-		this.megaEvolves = data.megaEvolves || '';
+		this.megaStone = data.megaStone || null;
 		this.zMove = data.zMove || null;
 		this.zMoveType = data.zMoveType || '';
 		this.zMoveFrom = data.zMoveFrom || '';
diff --git a/play.pokemonshowdown.com/src/battle-tooltips.ts b/play.pokemonshowdown.com/src/battle-tooltips.ts
index 78bcbb881b..4bc1eb5ec3 100644
--- a/play.pokemonshowdown.com/src/battle-tooltips.ts
+++ b/play.pokemonshowdown.com/src/battle-tooltips.ts
@@ -2620,7 +2620,7 @@ export class BattleStatGuesser {
 		let abilityid = toID(set.ability);
 
 		let species = this.dex.species.get(set.species || set.name!);
-		if (item.megaEvolves === species.name) species = this.dex.species.get(item.megaStone);
+		if (item.megaStone?.[species.name]) species = this.dex.species.get(item.megaStone[species.name]);
 		if (!species.exists) return '?';
 		let stats = species.baseStats;
 
diff --git a/play.pokemonshowdown.com/src/battle.ts b/play.pokemonshowdown.com/src/battle.ts
index 71c56a7c8d..0f9a845313 100644
--- a/play.pokemonshowdown.com/src/battle.ts
+++ b/play.pokemonshowdown.com/src/battle.ts
@@ -2473,7 +2473,11 @@ export class Battle {
 			let species = this.dex.species.get(newSpeciesForme);
 			if (nextArgs) {
 				if (nextArgs[0] === '-mega') {
-					species = this.dex.species.get(this.dex.items.get(nextArgs[3]).megaStone);
+					const item = this.dex.items.get(nextArgs[3]);
+					if (item.megaStone) {
+						const index = Object.values(item.megaStone).indexOf(species.name);
+						if (index >= 0) species = this.dex.species.get(Object.keys(item.megaStone)[index]);
+					}
 				} else if (nextArgs[0] === '-primal' && nextArgs.length > 2) {
 					if (nextArgs[2] === 'Red Orb') species = this.dex.species.get('Groudon-Primal');
 					if (nextArgs[2] === 'Blue Orb') species = this.dex.species.get('Kyogre-Primal');