Mime

Mime is a move where the Pokemon can learn its opponent's moves and do them. It only works during the battle unless the Pokemon uses Memorize. Only one Pokemon knows Memorize, so the other one cannot memorize the move. Luckily, the only Pokemon that know Mime are in the same evolutionary line, so the one that doesn't know Memorize can know the move when it evolves, and the Pokemon evolves with friendship, so all you need to do is walk around.
==Users==
*Mime Jr.
*Mr. Mime