Akash:
She doesn't want to wipe out humanity for nefarious reasons, she wants to play with her planet. Humans just don't take kindly to their cities being turned into deserts, lakes and forests while they are eaten by all the really cool new animals and plants she thinks up.
Think a kid building catles in a sandbox that 5 minutes ago was a sprawling ant empire. If Ants had superpowers that kid would be enemy #1, meanwhile the kid is like "Stinking ants, you're ruining my sandbox."
Oblivaeon threatens her world. She isn't changing sides of the coin, she's the same spirit, just has a different enemy, much worse than the little things that keep messing up her fun, and therefore worthy of much more drastic measures.
Baron:
I find Christopher's comment intriguing. I'm getting a Joker+Lex Luther vibe from it. Like Baron sulks around cursing LEgacy, and then suddenly has a brilliant idea that might work, throws it together as fast as he can and throws it at Legacy.
Like the Mars base trap, he gets not Legacy and is not at all prepared to deal with it. An elaborate large scale plan that hasn't been thought through very well, and he loves every minute of the fight.
For Luminary that works. He isn't thinking it through, there is no grand plan, just throwing inventions at Oblivaeon hoping one of them helps. I expect his deck to be amazing and have all kinds of colatoral damage potential. I can see him fighting along side Legacy, just like I can imagine the joker fighting his way through another villain's base to rescue Batman so he can defeat Batman himself.
Stuntman:
Love his progression, and it makes his tactics character make so much more sense. He becomes a hero and can show his face again only then to lose his powers, and thus his ability to be a hero. He can't take being weak again and goes back to villainy to get money to buy more powers.
I love the alternate version as well, Super action hero guy shows up to save the real world. Hopefully they remember his TiVo.