diff --git a/src/battle.ts b/src/battle.ts
index 3f2519df3e8..1e0605bdc64 100644
--- a/src/battle.ts
+++ b/src/battle.ts
@@ -157,7 +157,7 @@ export default class Battle {
   }
 
   addPostBattleLoot(enemyPokemon: EnemyPokemon): void {
-    this.postBattleLoot.push(...enemyPokemon.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && m.pokemonId === enemyPokemon.id && m.getTransferrable(false), false).map(i => {
+    this.postBattleLoot.push(...enemyPokemon.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && m.pokemonId === enemyPokemon.id && m.isTransferrable, false).map(i => {
       const ret = i as PokemonHeldItemModifier;
       ret.pokemonId = null;
       return ret;
diff --git a/src/data/ability.ts b/src/data/ability.ts
index 60850c59a2a..6a4e9e9c36a 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -1525,7 +1525,7 @@ export class PostAttackStealHeldItemAbAttr extends PostAttackAbAttr {
   applyPostAttack(pokemon: Pokemon, passive: boolean, defender: Pokemon, move: Move, hitResult: HitResult, args: any[]): Promise<boolean> {
     return new Promise<boolean>(resolve => {
       if (hitResult < HitResult.NO_EFFECT && (!this.condition || this.condition(pokemon, defender, move))) {
-        const heldItems = this.getTargetHeldItems(defender).filter(i => i.getTransferrable(false));
+        const heldItems = this.getTargetHeldItems(defender).filter(i => i.isTransferrable);
         if (heldItems.length) {
           const stolenItem = heldItems[pokemon.randSeedInt(heldItems.length)];
           pokemon.scene.tryTransferHeldItemModifier(stolenItem, pokemon, false).then(success => {
@@ -1543,7 +1543,7 @@ export class PostAttackStealHeldItemAbAttr extends PostAttackAbAttr {
 
   getTargetHeldItems(target: Pokemon): PokemonHeldItemModifier[] {
     return target.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-      && (m as PokemonHeldItemModifier).pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
+      && m.pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
   }
 }
 
@@ -1614,7 +1614,7 @@ export class PostDefendStealHeldItemAbAttr extends PostDefendAbAttr {
   applyPostDefend(pokemon: Pokemon, passive: boolean, attacker: Pokemon, move: Move, hitResult: HitResult, args: any[]): Promise<boolean> {
     return new Promise<boolean>(resolve => {
       if (hitResult < HitResult.NO_EFFECT && (!this.condition || this.condition(pokemon, attacker, move))) {
-        const heldItems = this.getTargetHeldItems(attacker).filter(i => i.getTransferrable(false));
+        const heldItems = this.getTargetHeldItems(attacker).filter(i => i.isTransferrable);
         if (heldItems.length) {
           const stolenItem = heldItems[pokemon.randSeedInt(heldItems.length)];
           pokemon.scene.tryTransferHeldItemModifier(stolenItem, pokemon, false).then(success => {
@@ -1632,7 +1632,7 @@ export class PostDefendStealHeldItemAbAttr extends PostDefendAbAttr {
 
   getTargetHeldItems(target: Pokemon): PokemonHeldItemModifier[] {
     return target.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-      && (m as PokemonHeldItemModifier).pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
+      && m.pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
   }
 }
 
diff --git a/src/data/move.ts b/src/data/move.ts
index d6752dd35a7..2c7ab94cc4c 100644
--- a/src/data/move.ts
+++ b/src/data/move.ts
@@ -1796,7 +1796,7 @@ export class StealHeldItemChanceAttr extends MoveEffectAttr {
       if (rand >= this.chance) {
         return resolve(false);
       }
-      const heldItems = this.getTargetHeldItems(target).filter(i => i.getTransferrable(false));
+      const heldItems = this.getTargetHeldItems(target).filter(i => i.isTransferrable);
       if (heldItems.length) {
         const poolType = target.isPlayer() ? ModifierPoolType.PLAYER : target.hasTrainer() ? ModifierPoolType.TRAINER : ModifierPoolType.WILD;
         const highestItemTier = heldItems.map(m => m.type.getOrInferTier(poolType)).reduce((highestTier, tier) => Math.max(tier, highestTier), 0);
@@ -1817,7 +1817,7 @@ export class StealHeldItemChanceAttr extends MoveEffectAttr {
 
   getTargetHeldItems(target: Pokemon): PokemonHeldItemModifier[] {
     return target.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-      && (m as PokemonHeldItemModifier).pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
+      && m.pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
   }
 
   getUserBenefitScore(user: Pokemon, target: Pokemon, move: Move): number {
@@ -1857,7 +1857,6 @@ export class RemoveHeldItemAttr extends MoveEffectAttr {
    * @returns {boolean} True if an item was removed
    */
   apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
-
     if (!this.berriesOnly && target.isPlayer()) { // "Wild Pokemon cannot knock off Player Pokemon's held items" (See Bulbapedia)
       return false;
     }
@@ -1870,7 +1869,8 @@ export class RemoveHeldItemAttr extends MoveEffectAttr {
     }
 
     // Considers entire transferrable item pool by default (Knock Off). Otherwise berries only if specified (Incinerate).
-    let heldItems = this.getTargetHeldItems(target).filter(i => i.getTransferrable(false));
+    let heldItems = this.getTargetHeldItems(target).filter(i => i.isTransferrable);
+
     if (this.berriesOnly) {
       heldItems = heldItems.filter(m => m instanceof BerryModifier && m.pokemonId === target.id, target.isPlayer());
     }
@@ -1894,7 +1894,7 @@ export class RemoveHeldItemAttr extends MoveEffectAttr {
 
   getTargetHeldItems(target: Pokemon): PokemonHeldItemModifier[] {
     return target.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-      && (m as PokemonHeldItemModifier).pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
+      && m.pokemonId === target.id, target.isPlayer()) as PokemonHeldItemModifier[];
   }
 
   getUserBenefitScore(user: Pokemon, target: Pokemon, move: Move): number {
@@ -1986,7 +1986,8 @@ export class StealEatBerryAttr extends EatBerryAttr {
     if (cancelled.value === true) {
       return false;
     }
-    const heldBerries = this.getTargetHeldBerries(target).filter(i => i.getTransferrable(false));
+
+    const heldBerries = this.getTargetHeldBerries(target);
     if (heldBerries.length <= 0) {
       return false;
     }
@@ -5479,7 +5480,7 @@ export class AttackedByItemAttr extends MoveAttr {
    */
   getCondition(): MoveConditionFunc {
     return (user: Pokemon, target: Pokemon, move: Move) => {
-      const heldItems = target.getHeldItems().filter(i => i.getTransferrable(true));
+      const heldItems = target.getHeldItems().filter(i => i.isTransferrable);
       if (heldItems.length === 0) {
         return false;
       }
@@ -6436,7 +6437,7 @@ export function initMoves() {
       .attr(AddBattlerTagAttr, BattlerTagType.DROWSY, false, true)
       .condition((user, target, move) => !target.status),
     new AttackMove(Moves.KNOCK_OFF, Type.DARK, MoveCategory.PHYSICAL, 65, 100, 20, -1, 0, 3)
-      .attr(MovePowerMultiplierAttr, (user, target, move) => target.getHeldItems().filter(i => i.getTransferrable(false)).length > 0 ? 1.5 : 1)
+      .attr(MovePowerMultiplierAttr, (user, target, move) => target.getHeldItems().filter(i => i.isTransferrable).length > 0 ? 1.5 : 1)
       .attr(RemoveHeldItemAttr, false),
     new AttackMove(Moves.ENDEAVOR, Type.NORMAL, MoveCategory.PHYSICAL, -1, 100, 5, -1, 0, 3)
       .attr(MatchHpAttr)
@@ -7067,7 +7068,7 @@ export function initMoves() {
     new StatusMove(Moves.QUASH, Type.DARK, 100, 15, -1, 0, 5)
       .unimplemented(),
     new AttackMove(Moves.ACROBATICS, Type.FLYING, MoveCategory.PHYSICAL, 55, 100, 15, -1, 0, 5)
-      .attr(MovePowerMultiplierAttr, (user, target, move) => Math.max(1, 2 - 0.2 * user.getHeldItems().filter(i => i.getTransferrable(true)).reduce((v, m) => v + m.stackCount, 0))),
+      .attr(MovePowerMultiplierAttr, (user, target, move) => Math.max(1, 2 - 0.2 * user.getHeldItems().filter(i => i.isTransferrable).reduce((v, m) => v + m.stackCount, 0))),
     new StatusMove(Moves.REFLECT_TYPE, Type.NORMAL, -1, 15, -1, 0, 5)
       .attr(CopyTypeAttr),
     new AttackMove(Moves.RETALIATE, Type.NORMAL, MoveCategory.PHYSICAL, 70, 100, 5, -1, 0, 5)
diff --git a/src/field/pokemon.ts b/src/field/pokemon.ts
index a4a82dfb31e..18a10f8b5d5 100644
--- a/src/field/pokemon.ts
+++ b/src/field/pokemon.ts
@@ -525,7 +525,7 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
     if (!this.scene) {
       return [];
     }
-    return this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && (m as PokemonHeldItemModifier).pokemonId === this.id, this.isPlayer()) as PokemonHeldItemModifier[];
+    return this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && m.pokemonId === this.id, this.isPlayer()) as PokemonHeldItemModifier[];
   }
 
   updateScale(): void {
@@ -3286,7 +3286,7 @@ export class PlayerPokemon extends Pokemon {
         this.scene.getParty().push(newPokemon);
         newPokemon.evolve(!isFusion ? newEvolution : new FusionSpeciesFormEvolution(this.id, newEvolution));
         const modifiers = this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-          && (m as PokemonHeldItemModifier).pokemonId === this.id, true) as PokemonHeldItemModifier[];
+          && m.pokemonId === this.id, true) as PokemonHeldItemModifier[];
         modifiers.forEach(m => {
           const clonedModifier = m.clone() as PokemonHeldItemModifier;
           clonedModifier.pokemonId = newPokemon.id;
@@ -3379,7 +3379,7 @@ export class PlayerPokemon extends Pokemon {
         partyMemberIndex--;
       }
       const fusedPartyMemberHeldModifiers = this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-        && (m as PokemonHeldItemModifier).pokemonId === pokemon.id, true) as PokemonHeldItemModifier[];
+        && m.pokemonId === pokemon.id, true) as PokemonHeldItemModifier[];
       const transferModifiers: Promise<boolean>[] = [];
       for (const modifier of fusedPartyMemberHeldModifiers) {
         transferModifiers.push(this.scene.tryTransferHeldItemModifier(modifier, this, false, modifier.getStackCount(), true, true));
diff --git a/src/modifier/modifier.ts b/src/modifier/modifier.ts
index a25f2a8a102..2e9efd2544d 100644
--- a/src/modifier/modifier.ts
+++ b/src/modifier/modifier.ts
@@ -470,6 +470,7 @@ export class TerastallizeAccessModifier extends PersistentModifier {
 
 export abstract class PokemonHeldItemModifier extends PersistentModifier {
   public pokemonId: integer;
+  readonly isTransferrable: boolean = true;
 
   constructor(type: ModifierType, pokemonId: integer, stackCount: integer) {
     super(type, stackCount);
@@ -491,10 +492,6 @@ export abstract class PokemonHeldItemModifier extends PersistentModifier {
     return super.shouldApply(args) && args.length && args[0] instanceof Pokemon && (this.pokemonId === -1 || (args[0] as Pokemon).id === this.pokemonId);
   }
 
-  getTransferrable(withinParty: boolean) {
-    return true;
-  }
-
   isIconVisible(scene: BattleScene): boolean {
     return this.getPokemon(scene).isOnField();
   }
@@ -570,6 +567,7 @@ export abstract class PokemonHeldItemModifier extends PersistentModifier {
 
 export abstract class LapsingPokemonHeldItemModifier extends PokemonHeldItemModifier {
   protected battlesLeft: integer;
+  readonly isTransferrable: boolean = false;
 
   constructor(type: ModifierTypes.ModifierType, pokemonId: integer, battlesLeft?: integer, stackCount?: integer) {
     super(type, pokemonId, stackCount);
@@ -606,6 +604,7 @@ export abstract class LapsingPokemonHeldItemModifier extends PokemonHeldItemModi
 
 export class TerastallizeModifier extends LapsingPokemonHeldItemModifier {
   public teraType: Type;
+  readonly isTransferrable: boolean = false;
 
   constructor(type: ModifierTypes.TerastallizeModifierType, pokemonId: integer, teraType: Type, battlesLeft?: integer, stackCount?: integer) {
     super(type, pokemonId, battlesLeft || 10, stackCount);
@@ -649,10 +648,6 @@ export class TerastallizeModifier extends LapsingPokemonHeldItemModifier {
     return ret;
   }
 
-  getTransferrable(withinParty: boolean): boolean {
-    return false;
-  }
-
   getScoreMultiplier(): number {
     return 1.25;
   }
@@ -664,6 +659,7 @@ export class TerastallizeModifier extends LapsingPokemonHeldItemModifier {
 
 export class PokemonBaseStatModifier extends PokemonHeldItemModifier {
   protected stat: Stat;
+  readonly isTransferrable: boolean = false;
 
   constructor(type: ModifierTypes.PokemonBaseStatBoosterModifierType, pokemonId: integer, stat: Stat, stackCount?: integer) {
     super(type, pokemonId, stackCount);
@@ -695,10 +691,6 @@ export class PokemonBaseStatModifier extends PokemonHeldItemModifier {
     return true;
   }
 
-  getTransferrable(_withinParty: boolean): boolean {
-    return false;
-  }
-
   getScoreMultiplier(): number {
     return 1.1;
   }
@@ -1878,6 +1870,7 @@ export class PokemonMultiHitModifier extends PokemonHeldItemModifier {
 export class PokemonFormChangeItemModifier extends PokemonHeldItemModifier {
   public formChangeItem: FormChangeItem;
   public active: boolean;
+  readonly isTransferrable: boolean = false;
 
   constructor(type: ModifierTypes.FormChangeItemModifierType, pokemonId: integer, formChangeItem: FormChangeItem, active: boolean, stackCount?: integer) {
     super(type, pokemonId, stackCount);
@@ -1916,10 +1909,6 @@ export class PokemonFormChangeItemModifier extends PokemonHeldItemModifier {
     return ret;
   }
 
-  getTransferrable(withinParty: boolean) {
-    return withinParty;
-  }
-
   getMaxHeldItemCount(pokemon: Pokemon): integer {
     return 1;
   }
@@ -2164,12 +2153,11 @@ export abstract class HeldItemTransferModifier extends PokemonHeldItemModifier {
       return false;
     }
 
-    const withinParty = pokemon.isPlayer() === targetPokemon.isPlayer();
     const poolType = pokemon.isPlayer() ? ModifierTypes.ModifierPoolType.PLAYER : pokemon.hasTrainer() ? ModifierTypes.ModifierPoolType.TRAINER : ModifierTypes.ModifierPoolType.WILD;
 
     const transferredModifierTypes: ModifierTypes.ModifierType[] = [];
     const itemModifiers = pokemon.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-        && (m as PokemonHeldItemModifier).pokemonId === targetPokemon.id && m.getTransferrable(withinParty), targetPokemon.isPlayer()) as PokemonHeldItemModifier[];
+        && m.pokemonId === targetPokemon.id && m.isTransferrable, targetPokemon.isPlayer()) as PokemonHeldItemModifier[];
     let highestItemTier = itemModifiers.map(m => m.type.getOrInferTier(poolType)).reduce((highestTier, tier) => Math.max(tier, highestTier), 0);
     let tierItemModifiers = itemModifiers.filter(m => m.type.getOrInferTier(poolType) === highestItemTier);
 
@@ -2214,6 +2202,7 @@ export abstract class HeldItemTransferModifier extends PokemonHeldItemModifier {
  * @see {@linkcode modifierTypes[MINI_BLACK_HOLE]}
  */
 export class TurnHeldItemTransferModifier extends HeldItemTransferModifier {
+  readonly isTransferrable: boolean = false;
   constructor(type: ModifierType, pokemonId: integer, stackCount?: integer) {
     super(type, pokemonId, stackCount);
   }
@@ -2226,10 +2215,6 @@ export class TurnHeldItemTransferModifier extends HeldItemTransferModifier {
     return new TurnHeldItemTransferModifier(this.type, this.pokemonId, this.stackCount);
   }
 
-  getTransferrable(withinParty: boolean) {
-    return withinParty;
-  }
-
   getTransferredItemCount(): integer {
     return this.getStackCount();
   }
diff --git a/src/phases.ts b/src/phases.ts
index fa8e18df092..ef24fca9b39 100644
--- a/src/phases.ts
+++ b/src/phases.ts
@@ -5160,7 +5160,7 @@ export class SelectModifierPhase extends BattlePhase {
           this.scene.ui.setModeWithoutClear(Mode.PARTY, PartyUiMode.MODIFIER_TRANSFER, -1, (fromSlotIndex: integer, itemIndex: integer, itemQuantity: integer, toSlotIndex: integer) => {
             if (toSlotIndex !== undefined && fromSlotIndex < 6 && toSlotIndex < 6 && fromSlotIndex !== toSlotIndex && itemIndex > -1) {
               const itemModifiers = this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-                    && (m as PokemonHeldItemModifier).getTransferrable(true) && (m as PokemonHeldItemModifier).pokemonId === party[fromSlotIndex].id) as PokemonHeldItemModifier[];
+                    && m.isTransferrable && m.pokemonId === party[fromSlotIndex].id) as PokemonHeldItemModifier[];
               const itemModifier = itemModifiers[itemIndex];
               this.scene.tryTransferHeldItemModifier(itemModifier, party[toSlotIndex], true, itemQuantity);
             } else {
diff --git a/src/ui/modifier-select-ui-handler.ts b/src/ui/modifier-select-ui-handler.ts
index 3cfd103b4e2..b3718b8854c 100644
--- a/src/ui/modifier-select-ui-handler.ts
+++ b/src/ui/modifier-select-ui-handler.ts
@@ -136,7 +136,7 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
 
     this.player = args[0];
 
-    const partyHasHeldItem = this.player && !!this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && (m as PokemonHeldItemModifier).getTransferrable(true)).length;
+    const partyHasHeldItem = this.player && !!this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && m.isTransferrable).length;
     const canLockRarities = !!this.scene.findModifier(m => m instanceof LockModifierTiersModifier);
 
     this.transferButtonContainer.setVisible(false);
diff --git a/src/ui/party-ui-handler.ts b/src/ui/party-ui-handler.ts
index e820c8cb0d2..c5e369e9193 100644
--- a/src/ui/party-ui-handler.ts
+++ b/src/ui/party-ui-handler.ts
@@ -306,7 +306,7 @@ export default class PartyUiHandler extends MessageUiHandler {
           || (option === PartyOption.RELEASE && this.partyUiMode === PartyUiMode.RELEASE)) {
           let filterResult: string;
           const getTransferrableItemsFromPokemon = (pokemon: PlayerPokemon) =>
-            this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && (m as PokemonHeldItemModifier).getTransferrable(true) && (m as PokemonHeldItemModifier).pokemonId === pokemon.id) as PokemonHeldItemModifier[];
+            this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && m.isTransferrable && m.pokemonId === pokemon.id) as PokemonHeldItemModifier[];
           if (option !== PartyOption.TRANSFER && option !== PartyOption.SPLICE) {
             filterResult = (this.selectFilter as PokemonSelectFilter)(pokemon);
             if (filterResult === null && (option === PartyOption.SEND_OUT || option === PartyOption.PASS_BATON)) {
@@ -482,7 +482,7 @@ export default class PartyUiHandler extends MessageUiHandler {
           if (this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER && !this.transferMode) {
             /** Initialize item quantities for the selected Pokemon */
             const itemModifiers = this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-              && (m as PokemonHeldItemModifier).getTransferrable(true) && (m as PokemonHeldItemModifier).pokemonId === this.scene.getParty()[this.cursor].id) as PokemonHeldItemModifier[];
+              && m.isTransferrable && m.pokemonId === this.scene.getParty()[this.cursor].id) as PokemonHeldItemModifier[];
             this.transferQuantities = itemModifiers.map(item => item.getStackCount());
             this.transferQuantitiesMax = itemModifiers.map(item => item.getStackCount());
           }
@@ -699,7 +699,7 @@ export default class PartyUiHandler extends MessageUiHandler {
 
     const itemModifiers = this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER
       ? this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-        && (m as PokemonHeldItemModifier).getTransferrable(true) && (m as PokemonHeldItemModifier).pokemonId === pokemon.id) as PokemonHeldItemModifier[]
+        && m.isTransferrable && m.pokemonId === pokemon.id) as PokemonHeldItemModifier[]
       : null;
 
     if (this.options.length) {
diff --git a/src/ui/summary-ui-handler.ts b/src/ui/summary-ui-handler.ts
index c55bedb7289..e20c7dd31a2 100644
--- a/src/ui/summary-ui-handler.ts
+++ b/src/ui/summary-ui-handler.ts
@@ -837,7 +837,7 @@ export default class SummaryUiHandler extends UiHandler {
       });
 
       const itemModifiers = (this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
-          && (m as PokemonHeldItemModifier).pokemonId === this.pokemon.id, true) as PokemonHeldItemModifier[])
+          && m.pokemonId === this.pokemon.id, true) as PokemonHeldItemModifier[])
         .sort(modifierSortFunc);
 
       itemModifiers.forEach((item, i) => {