I can't name all off the top but Mori is 100% a villain and is probably the strongest Holo being Death herself. Ame is by lore her enemy and her goal is to kill Mori. I guess Ina would be a villain depending on what the writers decide to do with her. I would see her going the, "Vilian who's defeated and joins the heroes and turns good over time" with a "had secret plans on betraying them later on" twist
The "Ina vs Mori" argument is null by default because eldritch creatures' powers vary widely and Ina has never specified what AO-chan can really do. Ina could easily be stronger than Mori by miles, OR she's probably not even stronger than Gura. It just depends. But I assume WE can safely say that without AO-chan, Ina is just a human and would die easily. But this also implies that AO-chan would EVERY leave Ina's side.
I don't think they'll have actual Holos be villains, but Mori would be final boss tier and Ame would probably be the one to kill her somehow or they'll pull a Naruto and make her their friend