He's wearing a rag that he tried to make look like Pikachu. Although it's a quiet, lonely Pokémon, if you try to look at what's under its rag, it will resist violently. A scholar who saw what was under its rag died from the shock. It belongs to team Rocket's Jessie and James. Team Rocket's Meowth is afraid of it because he has seen under Mimikyu's rag multiple times and fainted every time. All the pokemon food has been poisoned by the evil Dark Oak, starving every Pokémon.