diff --git a/src/data/pokemon-forms.ts b/src/data/pokemon-forms.ts
index 2c2d637c6f02..d6fe12a81860 100644
--- a/src/data/pokemon-forms.ts
+++ b/src/data/pokemon-forms.ts
@@ -138,7 +138,7 @@ export class SpeciesFormChange {
   public formKey: string;
   public trigger: SpeciesFormChangeTrigger;
   public quiet: boolean;
-  private conditions: SpeciesFormChangeCondition[];
+  public conditions: SpeciesFormChangeCondition[];
 
   constructor(speciesId: Species, preFormKey: string, evoFormKey: string, trigger: SpeciesFormChangeTrigger, quiet: boolean = false, ...conditions: SpeciesFormChangeCondition[]) {
     this.speciesId = speciesId;
@@ -375,6 +375,16 @@ export function getSpeciesFormChangeMessage(pokemon: Pokemon, formChange: Specie
   return `${prefix}${preName} changed form!`;
 }
 
+/**
+ * Gives a condition for form changing checking if a species is registered as caught in the player's dex data.
+ * Used for fusion forms such as Kyurem and Necrozma.
+ * @param species
+ * @returns A {@linkcode SpeciesFormChangeCondition} checking if that species is registered as caught
+ */
+function getSpeciesDependentFormChangeCondition(species: Species): SpeciesFormChangeCondition {
+  return new SpeciesFormChangeCondition(p => !!p.scene.gameData.dexData[species].caughtAttr);
+}
+
 interface PokemonFormChanges {
   [key: string]: SpeciesFormChange[]
 }
@@ -609,8 +619,8 @@ export const pokemonFormChanges: PokemonFormChanges = {
     new SpeciesFormChange(Species.LANDORUS, SpeciesFormKey.INCARNATE, SpeciesFormKey.THERIAN, new SpeciesFormChangeItemTrigger(FormChangeItem.REVEAL_GLASS))
   ],
   [Species.KYUREM]: [
-    new SpeciesFormChange(Species.KYUREM, "", "black", new SpeciesFormChangeItemTrigger(FormChangeItem.DARK_STONE)),
-    new SpeciesFormChange(Species.KYUREM, "", "white", new SpeciesFormChangeItemTrigger(FormChangeItem.LIGHT_STONE))
+    new SpeciesFormChange(Species.KYUREM, "", "black", new SpeciesFormChangeItemTrigger(FormChangeItem.DARK_STONE), false, getSpeciesDependentFormChangeCondition(Species.ZEKROM)),
+    new SpeciesFormChange(Species.KYUREM, "", "white", new SpeciesFormChangeItemTrigger(FormChangeItem.LIGHT_STONE), false, getSpeciesDependentFormChangeCondition(Species.RESHIRAM))
   ],
   [Species.KELDEO]: [
     new SpeciesFormChange(Species.KELDEO, "ordinary", "resolute", new SpeciesFormChangeMoveLearnedTrigger(Moves.SECRET_SWORD)),
@@ -700,8 +710,8 @@ export const pokemonFormChanges: PokemonFormChanges = {
     new SpeciesFormChange(Species.MIMIKYU, "busted", "disguised", new SpeciesFormChangeManualTrigger(), true)
   ],
   [Species.NECROZMA]: [
-    new SpeciesFormChange(Species.NECROZMA, "", "dawn-wings", new SpeciesFormChangeItemTrigger(FormChangeItem.N_LUNARIZER)),
-    new SpeciesFormChange(Species.NECROZMA, "", "dusk-mane", new SpeciesFormChangeItemTrigger(FormChangeItem.N_SOLARIZER))
+    new SpeciesFormChange(Species.NECROZMA, "", "dawn-wings", new SpeciesFormChangeItemTrigger(FormChangeItem.N_LUNARIZER), false, getSpeciesDependentFormChangeCondition(Species.LUNALA)),
+    new SpeciesFormChange(Species.NECROZMA, "", "dusk-mane", new SpeciesFormChangeItemTrigger(FormChangeItem.N_SOLARIZER), false, getSpeciesDependentFormChangeCondition(Species.SOLGALEO))
   ],
   [Species.MELMETAL]: [
     new SpeciesFormChange(Species.MELMETAL, "", SpeciesFormKey.GIGANTAMAX, new SpeciesFormChangeItemTrigger(FormChangeItem.MAX_MUSHROOMS))
@@ -787,8 +797,8 @@ export const pokemonFormChanges: PokemonFormChanges = {
     new SpeciesFormChange(Species.URSHIFU, "rapid-strike", SpeciesFormKey.GIGANTAMAX_RAPID, new SpeciesFormChangeItemTrigger(FormChangeItem.MAX_MUSHROOMS))
   ],
   [Species.CALYREX]: [
-    new SpeciesFormChange(Species.CALYREX, "", "ice", new SpeciesFormChangeItemTrigger(FormChangeItem.ICY_REINS_OF_UNITY)),
-    new SpeciesFormChange(Species.CALYREX, "", "shadow", new SpeciesFormChangeItemTrigger(FormChangeItem.SHADOW_REINS_OF_UNITY))
+    new SpeciesFormChange(Species.CALYREX, "", "ice", new SpeciesFormChangeItemTrigger(FormChangeItem.ICY_REINS_OF_UNITY), false, getSpeciesDependentFormChangeCondition(Species.GLASTRIER)),
+    new SpeciesFormChange(Species.CALYREX, "", "shadow", new SpeciesFormChangeItemTrigger(FormChangeItem.SHADOW_REINS_OF_UNITY), false, getSpeciesDependentFormChangeCondition(Species.SPECTRIER))
   ],
   [Species.ENAMORUS]: [
     new SpeciesFormChange(Species.ENAMORUS, SpeciesFormKey.INCARNATE, SpeciesFormKey.THERIAN, new SpeciesFormChangeItemTrigger(FormChangeItem.REVEAL_GLASS))
diff --git a/src/modifier/modifier-type.ts b/src/modifier/modifier-type.ts
index 5dfad42ad1d9..046b88d96cca 100644
--- a/src/modifier/modifier-type.ts
+++ b/src/modifier/modifier-type.ts
@@ -15,7 +15,7 @@ import { StatusEffect, getStatusEffectDescriptor } from "../data/status-effect";
 import { SpeciesFormKey } from "../data/pokemon-species";
 import BattleScene from "../battle-scene";
 import { VoucherType, getVoucherTypeIcon, getVoucherTypeName } from "../system/voucher";
-import { FormChangeItem, SpeciesFormChangeItemTrigger, pokemonFormChanges } from "../data/pokemon-forms";
+import { FormChangeItem, SpeciesFormChangeCondition, SpeciesFormChangeItemTrigger, pokemonFormChanges } from "../data/pokemon-forms";
 import { ModifierTier } from "./modifier-tier";
 import { Nature, getNatureName, getNatureStatMultiplier } from "#app/data/nature";
 import i18next from "i18next";
@@ -1028,7 +1028,8 @@ class FormChangeItemModifierTypeGenerator extends ModifierTypeGenerator {
       const formChangeItemPool = party.filter(p => pokemonFormChanges.hasOwnProperty(p.species.speciesId)).map(p => {
         const formChanges = pokemonFormChanges[p.species.speciesId];
         return formChanges.filter(fc => ((fc.formKey.indexOf(SpeciesFormKey.MEGA) === -1 && fc.formKey.indexOf(SpeciesFormKey.PRIMAL) === -1) || party[0].scene.getModifiers(Modifiers.MegaEvolutionAccessModifier).length)
-          && ((fc.formKey.indexOf(SpeciesFormKey.GIGANTAMAX) === -1 && fc.formKey.indexOf(SpeciesFormKey.ETERNAMAX) === -1) || party[0].scene.getModifiers(Modifiers.GigantamaxAccessModifier).length))
+          && ((fc.formKey.indexOf(SpeciesFormKey.GIGANTAMAX) === -1 && fc.formKey.indexOf(SpeciesFormKey.ETERNAMAX) === -1) || party[0].scene.getModifiers(Modifiers.GigantamaxAccessModifier).length)
+          && (!fc.conditions.length || fc.conditions.filter(cond => cond instanceof SpeciesFormChangeCondition && cond.predicate(p)).length))
           .map(fc => fc.findTrigger(SpeciesFormChangeItemTrigger) as SpeciesFormChangeItemTrigger)
           .filter(t => t && t.active && !p.scene.findModifier(m => m instanceof Modifiers.PokemonFormChangeItemModifier && m.pokemonId === p.id && m.formChangeItem === t.item));
       }).flat().flatMap(fc => fc.item);