[P2] Add "no switch-in" fail condition for Shed Tail and Baton Pass (#4777)

src/data/move.ts

@@ -5839,7 +5839,6 @@ export class ForceSwitchOutAttr extends MoveEffectAttr {
   }
 }
 
-
 export class ChillyReceptionAttr extends ForceSwitchOutAttr {
   apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
     user.scene.arena.trySetWeather(WeatherType.SNOW, true);
@@ -7063,6 +7062,11 @@ const targetSleptOrComatoseCondition: MoveConditionFunc = (user: Pokemon, target
 
 const failIfLastCondition: MoveConditionFunc = (user: Pokemon, target: Pokemon, move: Move) => user.scene.phaseQueue.find(phase => phase instanceof MovePhase) !== undefined;
 
+const failIfLastInPartyCondition: MoveConditionFunc = (user: Pokemon, target: Pokemon, move: Move) => {
+  const party: Pokemon[] = user.isPlayer() ? user.scene.getParty() : user.scene.getEnemyParty();
+  return party.some(pokemon => pokemon.isActive() && !pokemon.isOnField());
+};
+
 export type MoveAttrFilter = (attr: MoveAttr) => boolean;
 
 function applyMoveAttrsInternal(attrFilter: MoveAttrFilter, user: Pokemon | null, target: Pokemon | null, move: Move, args: any[]): Promise<void> {
@@ -7972,6 +7976,7 @@ export function initMoves() {
       .attr(StatusEffectAttr, StatusEffect.PARALYSIS),
     new SelfStatusMove(Moves.BATON_PASS, Type.NORMAL, -1, 40, -1, 0, 2)
       .attr(ForceSwitchOutAttr, true, SwitchType.BATON_PASS)
+      .condition(failIfLastInPartyCondition)
       .hidesUser(),
     new StatusMove(Moves.ENCORE, Type.NORMAL, 100, 5, -1, 0, 2)
       .attr(AddBattlerTagAttr, BattlerTagType.ENCORE, false, true)
@@ -10112,7 +10117,8 @@ export function initMoves() {
       .makesContact(),
     new SelfStatusMove(Moves.SHED_TAIL, Type.NORMAL, -1, 10, -1, 0, 9)
       .attr(AddSubstituteAttr, 0.5)
-      .attr(ForceSwitchOutAttr, true, SwitchType.SHED_TAIL),
+      .attr(ForceSwitchOutAttr, true, SwitchType.SHED_TAIL)
+      .condition(failIfLastInPartyCondition),
     new SelfStatusMove(Moves.CHILLY_RECEPTION, Type.ICE, -1, 10, -1, 0, 9)
       .attr(PreMoveMessageAttr, (user, move) => i18next.t("moveTriggers:chillyReception", { pokemonName: getPokemonNameWithAffix(user) }))
       .attr(ChillyReceptionAttr, true),

src/test/moves/shed_tail.test.ts

@@ -1,4 +1,5 @@
 import { SubstituteTag } from "#app/data/battler-tags";
+import { MoveResult } from "#app/field/pokemon";
 import { Abilities } from "#enums/abilities";
 import { Moves } from "#enums/moves";
 import { Species } from "#enums/species";
@@ -53,4 +54,18 @@ describe("Moves - Shed Tail", () => {
     expect(substituteTag).toBeDefined();
     expect(substituteTag?.hp).toBe(Math.floor(magikarp.getMaxHp() / 4));
   });
+
+  it("should fail if no ally is available to switch in", async () => {
+    await game.classicMode.startBattle([ Species.MAGIKARP ]);
+
+    const magikarp = game.scene.getPlayerPokemon()!;
+    expect(game.scene.getParty().length).toBe(1);
+
+    game.move.select(Moves.SHED_TAIL);
+
+    await game.phaseInterceptor.to("TurnEndPhase", false);
+
+    expect(magikarp.isOnField()).toBeTruthy();
+    expect(magikarp.getLastXMoves()[0].result).toBe(MoveResult.FAIL);
+  });
 });