Shout outs to Moémon, which is basically Pokemon with the Pokemon themselves re-skinned into anime girls. Excellent for making your friends uncomfortable, and you can easily swap save files between it and the regular game (assuming you're using an emulator) by just renaming everything; a friend and I played through Sigma Emerald (a hack of Emerald that was just it but better in nearly every way), and I loaded it up instead of the original to fuck with him every now and then. It's mostly only available for Gen III games, but there are some patches that work with some hacks (such as Sigma Emerald) at least, though I don't know where they are now (you'll probably have to do some digging if you want to play it).

Also, it's not sexual, I promise you; there is a bit of mild fanservice on some of the older looking Moémon (mainly cleavage from what I remember), but that's as far as it ever goes. It is definitely not pornographic or anything. Please don't judge me.