Everyone might be losing their minds of Ditto's appearance in Pokemon GO, courtesy of a recent update, but it wasn't the only creature added by Niantic. After poking through the patch's code, The Silph Road discovered 100 new entries for pokemon, living in a sort of limbo inside the game.
The new pokemon can be viewed via The Silph Road's rather helpful species stats database. What you'll want to do is turn on the "INCLUDE GEN 2 POKEMON" checkbox and then sort by species number. The new ones start at 152.
I can already here you saying "Yes, that's all good, but how do I catch these delicious new pokemans?". Well, while they're technically in the game, Niantic has left out a few vital bits and pieces so they can't actually appear:
Presently, no moveset data has been assigned to the new species. Furthermore, the moves themselves haven't even appeared in the code yet. This means a server and client-side change will have to occur before Gen 2 is launched. So nothing to hold your breath for, travelers. It may yet be a few more weeks or months. But Niantic has certainly been picking up momentum. At this point, it's anyone's guess when these major additions might find their way into the Pokemon GO universe.
Ditto, on the other hand, only need a server-side patch, which was easy for Niantic to deploy as it didn't require players to update anything. As such, it should be simple to deduce which pokemon are upcoming, as Niantic will push out a client update beforehand.
For now, you'll just have to continue farming your local Zubat population to extinction.
DITTO AND GENERATION 2 POKEMON HAVE NOW BEEN FOUND IN POKEMON GO APK [The Silph Road]