Okay, I've been implementing some, but I'm now not sure what to do with them
Ice Warriors -> Not yet implemented but will be just a merc unit I think.
Cybermen -> Could just claim they're being generic mercenary cyborgs since they don't look that much like Cybermen. Either that or they have to be an AOR unit where you dig out the cyberman tombs, but I feel like this should have some penalty not just "you freed the cybermen! yay cyber-buddies!"
Daleks - Possibly these have to be a faction? I just can't see Daleks working with anyone else. But I'm also not sure how they'd function as a faction either. Hm.