Ditto (Pokémon GO 53)

Abilities

This Pokémon can use the attacks of any Basic Pokémon in your discard pile, except for Pokémon with a Rule Box (Pokémon V, Pokémon-GX, etc. have Rule Boxes). (You still need the necessary Energy to use each attack.)

It can reconstitute its entire cellular structure to change into what it sees, but it returns to normal when it relaxes.