diff --git a/src/data/pokemon-species.ts b/src/data/pokemon-species.ts
index e7fe902956c..ff53fdb9392 100644
--- a/src/data/pokemon-species.ts
+++ b/src/data/pokemon-species.ts
@@ -888,17 +888,24 @@ export default class PokemonSpecies extends PokemonSpeciesForm implements Locali
   getCompatibleFusionSpeciesFilter(): PokemonSpeciesFilter {
     const hasEvolution = pokemonEvolutions.hasOwnProperty(this.speciesId);
     const hasPrevolution = pokemonPrevolutions.hasOwnProperty(this.speciesId);
-    const pseudoLegendary = this.subLegendary;
+    const subLegendary = this.subLegendary;
     const legendary = this.legendary;
     const mythical = this.mythical;
     return species => {
-      return (pseudoLegendary || legendary || mythical ||
-        (pokemonEvolutions.hasOwnProperty(species.speciesId) === hasEvolution
-        && pokemonPrevolutions.hasOwnProperty(species.speciesId) === hasPrevolution))
-        && species.subLegendary === pseudoLegendary
+      return (
+        subLegendary
+        || legendary
+        || mythical
+        || (
+          pokemonEvolutions.hasOwnProperty(species.speciesId) === hasEvolution
+          && pokemonPrevolutions.hasOwnProperty(species.speciesId) === hasPrevolution
+        )
+      )
+        && species.subLegendary === subLegendary
         && species.legendary === legendary
         && species.mythical === mythical
-        && (this.isTrainerForbidden() || !species.isTrainerForbidden());
+        && (this.isTrainerForbidden() || !species.isTrainerForbidden())
+        && species.speciesId !== Species.DITTO;
     };
   }
 
diff --git a/src/field/pokemon.ts b/src/field/pokemon.ts
index e0b7bf1094f..11811dcc9c4 100644
--- a/src/field/pokemon.ts
+++ b/src/field/pokemon.ts
@@ -2030,15 +2030,17 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
     const hasHiddenAbility = !Utils.randSeedInt(hiddenAbilityChance.value);
     const randAbilityIndex = Utils.randSeedInt(2);
 
-    const filter = !forStarter ? this.species.getCompatibleFusionSpeciesFilter()
-      : species => {
+    const filter = !forStarter ?
+      this.species.getCompatibleFusionSpeciesFilter()
+      : (species: PokemonSpecies) => {
         return pokemonEvolutions.hasOwnProperty(species.speciesId)
-      && !pokemonPrevolutions.hasOwnProperty(species.speciesId)
-      && !species.pseudoLegendary
-      && !species.legendary
-      && !species.mythical
-      && !species.isTrainerForbidden()
-      && species.speciesId !== this.species.speciesId;
+          && !pokemonPrevolutions.hasOwnProperty(species.speciesId)
+          && !species.subLegendary
+          && !species.legendary
+          && !species.mythical
+          && !species.isTrainerForbidden()
+          && species.speciesId !== this.species.speciesId
+          && species.speciesId !== Species.DITTO;
       };
 
     let fusionOverride: PokemonSpecies | undefined = undefined;