diff --git a/src/phases/stat-stage-change-phase.ts b/src/phases/stat-stage-change-phase.ts
index 4418c38c849..bfe19ea9ca5 100644
--- a/src/phases/stat-stage-change-phase.ts
+++ b/src/phases/stat-stage-change-phase.ts
@@ -36,6 +36,16 @@ export class StatStageChangePhase extends PokemonPhase {
   }
 
   start() {
+
+    // Check if multiple stats are being changed at the same time, then run SSCPhase for each of them
+    if (this.stats.length > 1) {
+      for (let i = 0; i < this.stats.length; i++) {
+        const stat = [ this.stats[i] ];
+        this.scene.unshiftPhase(new StatStageChangePhase(this.scene, this.battlerIndex, this.selfTarget, stat, this.stages, this.showMessage, this.ignoreAbilities, this.canBeCopied, this.onChange));
+      }
+      return this.end();
+    }
+
     const pokemon = this.getPokemon();
 
     if (!pokemon.isActive(true)) {
diff --git a/src/test/abilities/competitive.test.ts b/src/test/abilities/competitive.test.ts
new file mode 100644
index 00000000000..ecb276a1b8d
--- /dev/null
+++ b/src/test/abilities/competitive.test.ts
@@ -0,0 +1,72 @@
+import { Stat } from "#enums/stat";
+import { TurnInitPhase } from "#app/phases/turn-init-phase";
+import { Abilities } from "#enums/abilities";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import GameManager from "#test/utils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it } from "vitest";
+
+describe("Abilities - Competitive", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+
+    game.override.battleType("single")
+      .enemySpecies(Species.BEEDRILL)
+      .enemyMoveset(Moves.TICKLE)
+      .startingLevel(1)
+      .moveset([ Moves.SPLASH, Moves.CLOSE_COMBAT ])
+      .ability(Abilities.COMPETITIVE);
+  });
+
+  it("lower atk and def by 1 via tickle, then increase spatk by 4 via competitive", async () => {
+    await game.classicMode.startBattle([ Species.FLYGON ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.SPLASH);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(playerPokemon.getStatStage(Stat.ATK)).toBe(-1);
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(-1);
+    expect(playerPokemon.getStatStage(Stat.SPATK)).toBe(4);
+  });
+
+  it("lowering your own stats should not trigger competitive", async () => {
+    game.override.enemyMoveset(Moves.SPLASH);
+    await game.classicMode.startBattle([ Species.FLYGON ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.CLOSE_COMBAT);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(playerPokemon.getStatStage(Stat.SPDEF)).toBe(-1);
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(-1);
+    expect(playerPokemon.getStatStage(Stat.SPATK)).toBe(0);
+  });
+
+  it("white herb should remove only the negative effects", async () => {
+    game.override.startingHeldItems([{ name: "WHITE_HERB" }]);
+    await game.classicMode.startBattle([ Species.FLYGON ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.SPLASH);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(playerPokemon.getStatStage(Stat.ATK)).toBe(0);
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(0);
+    expect(playerPokemon.getStatStage(Stat.SPATK)).toBe(4);
+  });
+});
diff --git a/src/test/abilities/defiant.test.ts b/src/test/abilities/defiant.test.ts
new file mode 100644
index 00000000000..aa8d250dad7
--- /dev/null
+++ b/src/test/abilities/defiant.test.ts
@@ -0,0 +1,70 @@
+import { Stat } from "#enums/stat";
+import { TurnInitPhase } from "#app/phases/turn-init-phase";
+import { Abilities } from "#enums/abilities";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import GameManager from "#test/utils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it } from "vitest";
+
+describe("Abilities - Defiant", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+
+    game.override.battleType("single")
+      .enemySpecies(Species.BEEDRILL)
+      .enemyMoveset(Moves.TICKLE)
+      .startingLevel(1)
+      .moveset([ Moves.SPLASH, Moves.CLOSE_COMBAT ])
+      .ability(Abilities.DEFIANT);
+  });
+
+  it("lower atk and def by 1 via tickle, then increase atk by 4 via defiant", async () => {
+    await game.classicMode.startBattle([ Species.FLYGON ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.SPLASH);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(playerPokemon.getStatStage(Stat.ATK)).toBe(3);
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(-1);
+  });
+
+  it("lowering your own stats should not trigger defiant", async () => {
+    game.override.enemyMoveset(Moves.SPLASH);
+    await game.classicMode.startBattle([ Species.FLYGON ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.CLOSE_COMBAT);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(playerPokemon.getStatStage(Stat.SPDEF)).toBe(-1);
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(-1);
+    expect(playerPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("white herb should remove only the negative effects", async () => {
+    game.override.startingHeldItems([{ name: "WHITE_HERB" }]);
+    await game.classicMode.startBattle([ Species.FLYGON ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.SPLASH);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(0);
+    expect(playerPokemon.getStatStage(Stat.ATK)).toBe(3);
+  });
+});