That’s a Pokémon which was not previously in the game. Probably, it has something to do with the coming up Thanksgiving, but Ditto was added to the Pokemon Go and now it’s out there, Joinfo.com reports.
There is a catch about it: you can’t see Ditto on the map as Ditto. It’ll be shown as some other pokemon, like Pidgey, Ratata or Magikarps. But when you catch it, it will turn into Ditto.
Youtuber ProdigiesNationhas already shared his experience: