Ok, so I had a battlebond greninja from the password "battle-bond".
I installed the mod. Then the password greninja continued to work as it does normally (a.k.a. gen9 boosting instead of changing form to ash-greninja). I tried to breed it, but all 10 babies where either protean or torrent and using red-hots on them said "it won't have any effect".
Any help is appreciated, I would really enjoy the game much more with ash greninja < 3
edit: What I did it, I put the Ash-greninja.rb in patch/mods folder. Then put the respective graphics and icons to ovewrrite the existing greninja graphics and icons. Is there a problem because I already have the battlebond greninja from the password?
edit2: I'm an idiot, I tried to give battlebond to froakie