diff --git a/src/data/pokemon-species.ts b/src/data/pokemon-species.ts
index cfb5d2e23f3..09788e353cf 100644
--- a/src/data/pokemon-species.ts
+++ b/src/data/pokemon-species.ts
@@ -670,9 +670,6 @@ export default class PokemonSpecies extends PokemonSpeciesForm implements Locali
   }
 
   getTrainerSpeciesForLevel(level: number, allowEvolving: boolean = false, strength: PartyMemberStrength, currentWave: number = 0): Species {
-    if (currentWave === 20) { //Don't allow first gym leader wave 20 to evolve their mons
-      allowEvolving = false;
-    }
     return this.getSpeciesForLevel(level, allowEvolving, true, strength, currentWave);
   }
 
diff --git a/src/data/trainer-config.ts b/src/data/trainer-config.ts
index f473ae227bb..2d8c7a3cbc7 100644
--- a/src/data/trainer-config.ts
+++ b/src/data/trainer-config.ts
@@ -1170,6 +1170,9 @@ function getGymLeaderPartyTemplate(scene: BattleScene) {
 export function getRandomPartyMemberFunc(speciesPool: Species[], trainerSlot: TrainerSlot = TrainerSlot.TRAINER, ignoreEvolution: boolean = false, postProcess?: (enemyPokemon: EnemyPokemon) => void) {
   return (scene: BattleScene, level: number, strength: PartyMemberStrength) => {
     let species = Utils.randSeedItem(speciesPool);
+    if (scene.gameMode.isClassic && scene.currentBattle.waveIndex === 20) {
+      ignoreEvolution = true;
+    }
     if (!ignoreEvolution) {
       species = getPokemonSpecies(species).getTrainerSpeciesForLevel(level, true, strength, scene.currentBattle.waveIndex);
     }