Shedinja

Shedinja is one of the fictional species of Pokémon from the "Pokémon" media franchise owned by Nintendo and Game Freak.
It is a Bug/Ghost type Pokemon from the third generation of games, Ruby, Sapphire and Emerald. It is evolved from a Nincada when there's a free space in the player's party. Shedinja is notable because it only takes damage from super effective attacks and has one HP.