Wow, yeah. Love all of those examples. I suppose my biggest worry for the game is that all characters are going to play almost identically, with a standard attack that can combo and a special move that is related to their abilities.
Considering we have either a keyboard and mouse, just keyboard or a gamepad to work with, it would make sense to me to overall, make more use of the buttons or combos available.
If it were button based (A S D C, A B X Y, etc.) I can see something with an ability cooldown system where everybody has specific abilities that fall into categories, direct attack, area of effect, conical and defense, maybe. With a specific "super" that would charge based on attack combos. All in addition to a basic attack that would have no cooldown, or only have to cooldowns and if you don't ration them well you're left with no offense for a bit.
Direct: Darwin, gorilla arm slam; Tesla, lighting punch; Curie, uranium rod smack; Tapputi, scythe etc.
AOE: Darwin, giraffe neck flail; Tesla, radial shockwave; Curie, a tiny atom bomb; Tapputi, poison mist
Conical: Darwin, elephant charge; Tesla, linear lightning strikes; Curie, radioactive ray; Tapputi, a paralyzing perfume
I like all the examples you gave and they would all certainly work just as well, the power button definitely sounds like an interesting concept but I would wonder how to implement directional triggers in a game that also has a Z axis. (Edit: you already covered that one)
I'm glad you called me out on that, thanks! ^_^