diff --git a/src/battle.ts b/src/battle.ts
index 77aeaca0cac..a5f1b830cc7 100644
--- a/src/battle.ts
+++ b/src/battle.ts
@@ -2,7 +2,7 @@ import BattleScene from "./battle-scene";
 import { Command } from "./ui/command-ui-handler";
 import * as Utils from "./utils";
 import Trainer, { TrainerVariant } from "./field/trainer";
-import { GameMode, GameModes } from "./game-mode";
+import { GameMode } from "./game-mode";
 import { MoneyMultiplierModifier, PokemonHeldItemModifier } from "./modifier/modifier";
 import { PokeballType } from "#enums/pokeball";
 import { trainerConfigs } from "#app/data/trainer-config";
@@ -28,13 +28,6 @@ export enum ClassicFixedBossWaves {
   EVIL_BOSS_2 = 165,
 }
 
-export enum EndlessBossType {
-  STANDARD = 50,
-  ETERNATUS = 250,
-  ETERNAMAX = 1000,
-  NONE
-}
-
 export enum BattleType {
   WILD,
   TRAINER,
@@ -445,32 +438,6 @@ export default class Battle {
   isBattleMysteryEncounter(): boolean {
     return this.battleType === BattleType.MYSTERY_ENCOUNTER;
   }
-
-  /**
-   * @returns `true` if the current battle is against classic mode's final boss
-   */
-  isBattleClassicFinalBoss(): boolean {
-    return (this.gameMode.modeId === GameModes.CLASSIC || this.gameMode.modeId === GameModes.CHALLENGE) && this.waveIndex === 200;
-  }
-
-  /**
-   * Uses modulos to determine what type of boss is faced by the player in Endless mode.
-   * @returns the type of Endless boss faced by the player {@linkcode EndlessBossType}
-   */
-  getEndlessBossType(): EndlessBossType {
-    if (this.gameMode.modeId !== GameModes.ENDLESS && this.gameMode.modeId !== GameModes.SPLICED_ENDLESS) {
-      return EndlessBossType.NONE;
-    } else {
-      if (!(this.waveIndex % EndlessBossType.ETERNAMAX)) {
-        return EndlessBossType.ETERNAMAX;
-      } else if (!(this.waveIndex % EndlessBossType.ETERNATUS)) {
-        return EndlessBossType.ETERNATUS;
-      } else if (!(this.waveIndex % EndlessBossType.STANDARD)) {
-        return EndlessBossType.STANDARD;
-      }
-      return EndlessBossType.NONE;
-    }
-  }
 }
 
 export class FixedBattle extends Battle {
diff --git a/src/game-mode.ts b/src/game-mode.ts
index 8f1bb9356e6..fc9bde0da58 100644
--- a/src/game-mode.ts
+++ b/src/game-mode.ts
@@ -230,6 +230,13 @@ export class GameMode implements GameModeConfig {
     return waveIndex % 10 === 0;
   }
 
+  /**
+   * @returns `true` if the current battle is against classic mode's final boss
+   */
+  isBattleClassicFinalBoss(waveIndex: number): boolean {
+    return (this.modeId === GameModes.CLASSIC || this.modeId === GameModes.CHALLENGE) && this.isWaveFinal(waveIndex);
+  }
+
   /**
      * Every 50 waves of an Endless mode is a boss
      * At this time it is paradox pokemon
diff --git a/src/phases/encounter-phase.ts b/src/phases/encounter-phase.ts
index 40aa61bc457..2e6b7e03c11 100644
--- a/src/phases/encounter-phase.ts
+++ b/src/phases/encounter-phase.ts
@@ -1,4 +1,4 @@
-import { BattlerIndex, BattleType, EndlessBossType } from "#app/battle";
+import { BattlerIndex, BattleType } from "#app/battle";
 import BattleScene from "#app/battle-scene";
 import { PLAYER_PARTY_MAX_SIZE } from "#app/constants";
 import { applyAbAttrs, SyncEncounterNatureAbAttr } from "#app/data/ability";
@@ -217,7 +217,7 @@ export class EncounterPhase extends BattlePhase {
         regenerateModifierPoolThresholds(this.scene.getEnemyField(), battle.battleType === BattleType.TRAINER ? ModifierPoolType.TRAINER : ModifierPoolType.WILD);
         this.scene.generateEnemyModifiers();
         // This checks if the current battle is an Endless E-Max battle/Classic final boss and sets the MBH held by the boss to untransferrable
-        if (this.scene.currentBattle.getEndlessBossType() === EndlessBossType.ETERNAMAX || battle.isBattleClassicFinalBoss()) {
+        if (this.scene.gameMode.isEndlessMajorBoss(this.scene.currentBattle.waveIndex) || this.scene.gameMode.isBattleClassicFinalBoss(this.scene.currentBattle.waveIndex)) {
           const enemyPokemon = this.scene.getEnemyPokemon();
           if (enemyPokemon) {
             const bossMBH = this.scene.findModifier(m => m instanceof TurnHeldItemTransferModifier && m.pokemonId === enemyPokemon.id, false) as TurnHeldItemTransferModifier;