I think I just realized the most likely in lore reason for Ash-Greninja being a thing over Ash-Pikachu is it has to be a Fully Evolved Pokémon like Megas.
I think I just realized the most likely in lore reason for Ash-Greninja being a thing over Ash-Pikachu is it has to be a Fully Evolved Pokémon like Megas.