Mew

Mew is a Legendary Pokémon that is generally regarded as the most powerful and rarest Pokémon of all time. It inhabits a jungle in South America, and can learn any TM. It has made various apperances in the Pokémon games, but most of these appearances are sideaffects of the Mew Glitch. Its only official appearance is in Pokémon Emerald, where it appeared on Faraway Island.