Automatically activate Booster Energy during weather/terrain changes

data/abilities.ts

@@ -605,7 +605,7 @@ export const Abilities: import('../sim/dex-abilities').AbilityDataTable = {
 		},
 		onUpdate(pokemon) {
 			if (this.gameType !== 'doubles') return;
-			// don't run between when a Pokemon switches in and the resulting onSwitchIn event
+			// don't run between when a Pokemon switches in and the resulting SwitchIn event
 			if (this.queue.peek()?.choice === 'runSwitch') return;
 
 			const ally = pokemon.allies()[0];
@@ -3438,10 +3438,20 @@ export const Abilities: import('../sim/dex-abilities').AbilityDataTable = {
 			// Protosynthesis is not affected by Utility Umbrella
 			if (this.field.isWeather('sunnyday')) {
 				pokemon.addVolatile('protosynthesis');
-			} else if (!pokemon.volatiles['protosynthesis']?.fromBooster && !this.field.isWeather('sunnyday')) {
+			} else if (!pokemon.volatiles['protosynthesis'] && pokemon.hasItem('boosterenergy')) {
+				pokemon.useItem();
+			} else if (!pokemon.volatiles['protosynthesis']?.fromBooster) {
 				pokemon.removeVolatile('protosynthesis');
 			}
 		},
+		onUpdate(pokemon) {
+			// don't run between when a Pokemon switches in and the resulting SwitchIn event
+			if (this.queue.peek()?.choice === 'runSwitch') return;
+
+			if (!pokemon.volatiles['protosynthesis'] && !this.field.isWeather('sunnyday') && pokemon.hasItem('boosterenergy')) {
+				pokemon.useItem();
+			}
+		},
 		onEnd(pokemon) {
 			delete pokemon.volatiles['protosynthesis'];
 			this.add('-end', pokemon, 'Protosynthesis', '[silent]');
@@ -3574,10 +3584,20 @@ export const Abilities: import('../sim/dex-abilities').AbilityDataTable = {
 		onTerrainChange(pokemon) {
 			if (this.field.isTerrain('electricterrain')) {
 				pokemon.addVolatile('quarkdrive');
+			} else if (!pokemon.volatiles['quarkdrive'] && pokemon.hasItem('boosterenergy')) {
+				pokemon.useItem();
 			} else if (!pokemon.volatiles['quarkdrive']?.fromBooster) {
 				pokemon.removeVolatile('quarkdrive');
 			}
 		},
+		onUpdate(pokemon) {
+			// don't run between when a Pokemon switches in and the resulting SwitchIn event
+			if (this.queue.peek()?.choice === 'runSwitch') return;
+
+			if (!pokemon.volatiles['quarkdrive'] && !this.field.isTerrain('electricterrain') && pokemon.hasItem('boosterenergy')) {
+				pokemon.useItem();
+			}
+		},
 		onEnd(pokemon) {
 			delete pokemon.volatiles['quarkdrive'];
 			this.add('-end', pokemon, 'Quark Drive', '[silent]');

data/items.ts

@@ -613,20 +613,11 @@ export const Items: import('../sim/dex-items').ItemDataTable = {
 		fling: {
 			basePower: 30,
 		},
-		onSwitchInPriority: -2,
-		onStart(pokemon) {
-			this.effectState.started = true;
-			((this.effect as any).onUpdate as (p: Pokemon) => void).call(this, pokemon);
+		onUseItem(item, pokemon) {
+			return ['protosynthesis', 'quarkdrive'].includes(pokemon.ability);
 		},
-		onUpdate(pokemon) {
-			if (!this.effectState.started || pokemon.transformed) return;
-
-			if (pokemon.hasAbility('protosynthesis') && !this.field.isWeather('sunnyday') && pokemon.useItem()) {
-				pokemon.addVolatile('protosynthesis');
-			}
-			if (pokemon.hasAbility('quarkdrive') && !this.field.isTerrain('electricterrain') && pokemon.useItem()) {
-				pokemon.addVolatile('quarkdrive');
-			}
+		onUse(pokemon) {
+			pokemon.addVolatile(pokemon.ability);
 		},
 		onTakeItem(item, source) {
 			if (source.baseSpecies.tags.includes("Paradox")) return false;

data/mods/gen9dlc1/abilities.ts

@@ -13,6 +13,8 @@ export const Abilities: import('../../../sim/dex-abilities').ModdedAbilityDataTa
 			// Protosynthesis is not affected by Utility Umbrella
 			if (this.field.isWeather('sunnyday')) {
 				pokemon.addVolatile('protosynthesis');
+			} else if (!pokemon.volatiles['protosynthesis'] && pokemon.hasItem('boosterenergy')) {
+				pokemon.useItem();
 			} else if (!pokemon.volatiles['protosynthesis']?.fromBooster && this.field.weather !== 'sunnyday') {
 				// Protosynthesis will not deactivite if Sun is suppressed, hence the direct ID check (isWeather respects supression)
 				pokemon.removeVolatile('protosynthesis');

sim/pokemon.ts

@@ -1492,9 +1492,6 @@ export class Pokemon {
 
 		this.volatileStaleness = undefined;
 
-		delete this.abilityState.started;
-		delete this.itemState.started;
-
 		this.setSpecies(this.baseSpecies);
 	}
 

test/sim/items/boosterenergy.js

@@ -24,4 +24,19 @@ describe('Booster Energy', function () {
 		assert.equal(bundle.volatiles['quarkdrive'].bestStat, 'spa',
 			`Iron Bundle's Speed should have been lowered before Booster Energy activated, boosting its SpA instead.`);
 	});
+
+	it(`should activate right after weather changes`, function () {
+		battle = common.createBattle({gameType: 'doubles'}, [[
+			{species: 'Ninetales-Alola', ability: 'snowwarning', moves: ['sleeptalk']},
+			{species: 'Roaring Moon', item: 'boosterenergy', ability: 'protosynthesis', moves: ['sleeptalk']},
+		], [
+			{species: 'Incineroar', ability: 'intimidate', moves: ['sleeptalk']},
+			{species: 'Torkoal', ability: 'drought', moves: ['sleeptalk']},
+		]]);
+
+		const roaringMoon = battle.p1.active[1];
+		assert(roaringMoon.volatiles['protosynthesis'].fromBooster);
+		assert.equal(roaringMoon.volatiles['protosynthesis'].bestStat, 'atk');
+		assert.equal(battle.field.weather, 'sunnyday');
+	});
 });