A Basic Pokemon Card of type Colorless with the title Ditto and 70 HP of rarity Rare Holo from the set Boundaries Crossed and the flavor text: It can reconstitute its entire cellular structure to change into what it sees, but it returns to normal when it relaxes. It has the ability Transform with the description: During your turn (before your attack), you may put a Basic Pokemon from your hand on top of this Pokemon. (This does not count as playing that Pokemon or evolving.) This Pokemon is now that Pokemon. (Any cards attached to this Pokemon, damage counters, Special Conditions, turns in play, and any other effects remain on the new Pokemon.) It has weakness against Fighting 2. 
Ditto