diff --git a/src/phases/select-modifier-phase.ts b/src/phases/select-modifier-phase.ts
index b4c49299536..f99c921412f 100644
--- a/src/phases/select-modifier-phase.ts
+++ b/src/phases/select-modifier-phase.ts
@@ -31,6 +31,8 @@ import Overrides from "#app/overrides";
 import type { CustomModifierSettings } from "#app/modifier/modifier-type";
 import { isNullOrUndefined, NumberHolder } from "#app/utils/common";
 
+export type ModifierSelectCallback = (rowCursor: number, cursor: number) => boolean;
+
 export class SelectModifierPhase extends BattlePhase {
   public readonly phaseName = "SelectModifierPhase";
   private rerollCount: number;
@@ -124,7 +126,7 @@ export class SelectModifierPhase extends BattlePhase {
   }
 
   // Pick a modifier from among the rewards and apply it
-  private selectRewardModifierOption(cursor: number, modifierSelectCallback): boolean {
+  private selectRewardModifierOption(cursor: number, modifierSelectCallback: ModifierSelectCallback): boolean {
     if (this.typeOptions.length === 0) {
       globalScene.ui.clearText();
       globalScene.ui.setMode(UiMode.MESSAGE);
@@ -136,7 +138,11 @@ export class SelectModifierPhase extends BattlePhase {
   }
 
   // Pick a modifier from the shop and apply it
-  private selectShopModifierOption(rowCursor: number, cursor: number, modifierSelectCallback): boolean {
+  private selectShopModifierOption(
+    rowCursor: number,
+    cursor: number,
+    modifierSelectCallback: ModifierSelectCallback,
+  ): boolean {
     const shopOptions = getPlayerShopModifierTypeOptionsForWave(
       globalScene.currentBattle.waveIndex,
       globalScene.getWaveMoneyAmount(1),
@@ -160,7 +166,11 @@ export class SelectModifierPhase extends BattlePhase {
   }
 
   // Apply a chosen modifier: do an effect or open the party menu
-  private applyChosenModifier(modifierType: ModifierType, cost: number, modifierSelectCallback): boolean {
+  private applyChosenModifier(
+    modifierType: ModifierType,
+    cost: number,
+    modifierSelectCallback: ModifierSelectCallback,
+  ): boolean {
     if (modifierType instanceof PokemonModifierType) {
       if (modifierType instanceof FusePokemonModifierType) {
         this.openFusionMenu(modifierType, cost, modifierSelectCallback);
@@ -198,7 +208,7 @@ export class SelectModifierPhase extends BattlePhase {
   }
 
   // Transfer modifiers among party pokemon
-  private openModifierTransferScreen(modifierSelectCallback) {
+  private openModifierTransferScreen(modifierSelectCallback: ModifierSelectCallback) {
     const party = globalScene.getPlayerParty();
     globalScene.ui.setModeWithoutClear(
       UiMode.PARTY,
@@ -280,7 +290,11 @@ export class SelectModifierPhase extends BattlePhase {
   }
 
   // Opens the party menu specifically for fusions
-  private openFusionMenu(modifierType: PokemonModifierType, cost: number, modifierSelectCallback): void {
+  private openFusionMenu(
+    modifierType: PokemonModifierType,
+    cost: number,
+    modifierSelectCallback: ModifierSelectCallback,
+  ): void {
     const party = globalScene.getPlayerParty();
     globalScene.ui.setModeWithoutClear(
       UiMode.PARTY,
@@ -306,7 +320,11 @@ export class SelectModifierPhase extends BattlePhase {
   }
 
   // Opens the party menu to apply one of various modifiers
-  private openModifierMenu(modifierType: PokemonModifierType, cost: number, modifierSelectCallback): void {
+  private openModifierMenu(
+    modifierType: PokemonModifierType,
+    cost: number,
+    modifierSelectCallback: ModifierSelectCallback,
+  ): void {
     const party = globalScene.getPlayerParty();
     const pokemonModifierType = modifierType as PokemonModifierType;
     const isMoveModifier = modifierType instanceof PokemonMoveModifierType;
@@ -374,7 +392,7 @@ export class SelectModifierPhase extends BattlePhase {
 
   // Function that resets the reward selection screen,
   // e.g. after pressing cancel in the party ui or while learning a move
-  private resetModifierSelect(modifierSelectCallback) {
+  private resetModifierSelect(modifierSelectCallback: ModifierSelectCallback) {
     globalScene.ui.setMode(
       UiMode.MODIFIER_SELECT,
       this.isPlayer(),