diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index d30d8adba38..167a108e58c 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -15,29 +15,8 @@ on:
     types: [checks_requested]
 
 jobs:
-  pre-test:
-    name: Run Pre-test
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check out Git repository
-        uses: actions/checkout@v4
-        with:
-          submodules: 'recursive'
-          path: tests-action
-      - name: Set up Node.js
-        uses: actions/setup-node@v4
-        with:
-          node-version: 20
-      - name: Install Node.js dependencies
-        working-directory: tests-action
-        run: npm ci
-      - name: Run Pre-test
-        working-directory: tests-action
-        run: npx vitest run --project pre ${{ !runner.debug && '--silent' || '' }}
-
   run-tests:
     name: Run Tests 
-    needs: [pre-test]
     strategy:
       matrix:
         shard: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
diff --git a/src/overrides.ts b/src/overrides.ts
index 882a634ff90..3a9a54e740b 100644
--- a/src/overrides.ts
+++ b/src/overrides.ts
@@ -254,6 +254,11 @@ class DefaultOverrides {
    * Note that, for all items in the array, `count` is not used.
    */
   readonly ITEM_REWARD_OVERRIDE: ModifierOverride[] = [];
+
+  /**
+   * If `true`, disable all non-scripted opponent trainer encounters.
+   */
+  readonly DISABLE_STANDARD_TRAINERS_OVERRIDE: boolean = false;
 }
 
 export const defaultOverrides = new DefaultOverrides();
diff --git a/test/testUtils/gameManager.ts b/test/testUtils/gameManager.ts
index 7e0231f4232..981a2dbd2f1 100644
--- a/test/testUtils/gameManager.ts
+++ b/test/testUtils/gameManager.ts
@@ -57,6 +57,7 @@ import fs from "node:fs";
 import { expect, vi } from "vitest";
 import { globalScene } from "#app/global-scene";
 import type StarterSelectUiHandler from "#app/ui/starter-select-ui-handler";
+import { MockFetch } from "./mocks/mockFetch";
 
 /**
  * Class to manage the game state and transitions between phases.
@@ -122,9 +123,12 @@ export default class GameManager {
     this.settings = new SettingsHelper(this);
     this.reload = new ReloadHelper(this);
     this.modifiers = new ModifierHelper(this);
+    this.override.sanitizeOverrides();
 
     // Disables Mystery Encounters on all tests (can be overridden at test level)
     this.override.mysteryEncounterChance(0);
+
+    global.fetch = vi.fn(MockFetch) as any;
   }
 
   /**
diff --git a/test/testUtils/helpers/overridesHelper.ts b/test/testUtils/helpers/overridesHelper.ts
index e69e05bce45..8a78565e4d5 100644
--- a/test/testUtils/helpers/overridesHelper.ts
+++ b/test/testUtils/helpers/overridesHelper.ts
@@ -6,7 +6,7 @@ import type { GameModes } from "#app/game-mode";
 import { getGameMode } from "#app/game-mode";
 import type { ModifierOverride } from "#app/modifier/modifier-type";
 import type { BattleStyle } from "#app/overrides";
-import Overrides from "#app/overrides";
+import Overrides, { defaultOverrides } from "#app/overrides";
 import type { Unlockables } from "#app/system/unlockables";
 import { Biome } from "#enums/biome";
 import { Moves } from "#enums/moves";
@@ -15,8 +15,9 @@ import type { MysteryEncounterType } from "#enums/mystery-encounter-type";
 import { Species } from "#enums/species";
 import { StatusEffect } from "#enums/status-effect";
 import type { WeatherType } from "#enums/weather-type";
-import { vi } from "vitest";
+import { expect, vi } from "vitest";
 import { GameManagerHelper } from "./gameManagerHelper";
+import { shiftCharCodes } from "#app/utils";
 
 /**
  * Helper to handle overrides in tests
@@ -226,12 +227,7 @@ export class OverridesHelper extends GameManagerHelper {
    * @returns `this`
    */
   public disableTrainerWaves(): this {
-    const realFn = getGameMode;
-    vi.spyOn(GameMode, "getGameMode").mockImplementation((gameMode: GameModes) => {
-      const mode = realFn(gameMode);
-      mode.hasTrainers = false;
-      return mode;
-    });
+    vi.spyOn(Overrides, "DISABLE_STANDARD_TRAINERS_OVERRIDE");
     this.log("Standard trainer waves are disabled!");
     return this;
   }
@@ -263,11 +259,8 @@ export class OverridesHelper extends GameManagerHelper {
    * @returns `this`
    */
   public seed(seed: string): this {
-    vi.spyOn(this.game.scene, "resetSeed").mockImplementation(() => {
-      this.game.scene.waveSeed = seed;
-      Phaser.Math.RND.sow([seed]);
-      this.game.scene.rngCounter = 0;
-    });
+    // Shift the seed here with a negative wave number, to compensate for `resetSeed()` shifting the seed itself.
+    this.game.scene.setSeed(shiftCharCodes(seed, (this.game.scene.currentBattle?.waveIndex ?? 0) * -1));
     this.game.scene.resetSeed();
     this.log(`Seed set to "${seed}"!`);
     return this;
@@ -539,4 +532,14 @@ export class OverridesHelper extends GameManagerHelper {
   private log(...params: any[]) {
     console.log("Overrides:", ...params);
   }
+
+  public sanitizeOverrides(): void {
+    for (const key of Object.keys(defaultOverrides)) {
+      if (Overrides[key] !== defaultOverrides[key]) {
+        vi.spyOn(Overrides, key as any, "get").mockReturnValue(defaultOverrides[key]);
+      }
+    }
+    expect(Overrides).toEqual(defaultOverrides);
+    this.log("Sanitizing all overrides!");
+  }
 }