Searching for a Ditto to get yourself one step closer to achieving Mew? Here’s a list of the Pokémon you need to be looking for.
Hoothoot
Sentret
Yanma
Taillow
Whismur
Gulpin
Zigzagoon
Gastly
Pidgey
Rattata
Zubat
Meltan (new)
Unfortunately, you won’t know if a Pokémon is a Ditto in disguise until after you’ve caught it. When you do find one, “Oh?” will appear and a Ditto will emerge. (The only exception to this is the new Pokémon, Meltan, which is guaranteed to turn into a Ditto every time).
Although it’s been tough in the past to find a Ditto, with the increased spawn rate that accompanied the new research feature and the recent addition of Meltan, this once inefficient task is now achievable in a relatively small amount of time.
Good luck in your search.
Source: Niantic