What pokemon can turn into dittos after you catch them?

I believe the current list is:

Pidgey
Ratatta
Zubat
Mankey
Yanma
Hoothoot
Remoraid
Sentret
Zigzagoon
Gulpin
Whismur

The list has changed a few times over the game's history, some species even being removed as eligible, so it can be tough to find a definitive list.

I freaking raged when my Yanma turned into a Ditto...

Anything that has a shiny form released is not able to be a ditto.