Yanma

Yanma is a rare Ghost-type Pokémon from Johto region. It does not evolve into nor from any other Pokémon currently.

Trivia

 * Yanma is one of the Pokémon that Ditto can appear as in wild.
 * Since Generation IV of core series games, Yanma evolves into Yanmega, but in Pokémon GO it's currently not possible.