The game updated this week, and the blog Silph Road discovered that Ditto is one of the new additions. Over the past day or so, players have started posting screenshots of the Pokémon on social media.
Ditto disguises itself as other Pokémon, so when you encounter it in the wild, it will look like a normal Pidgey, Rattata, or whatever. It only reveals itself after it’s been caught, like in this video from the game.
One of Ditto’s moves is “transform,” meaning it can change into its opponent’s shape during Pokémon battles.
H/T to Mashable