Is this a Delinquent or a Transformed? A Hulk-like character but who only transforms into a monster when they don’t have enough adrenaline in their system. If they get bored they literally become a destructive monster, but otherwise they are a redline action junkie.
That could also be a really interesting Janus who swaps their Freak for the Mundane. But both the Delinquent or the Transformed would also work well. Make the most of that “when you help a teammate through destructive, criminal, or rule-breaking actions” move as the Delinquent or basically any of the Transformed moves.
An Outsider or Newborn character: a toy who came to life. They might be the favorite plaything of a young Franklin Richards-type psychic or mutant, an action figure caught in the blast radius of powerful magic, or just the miraculous answer to a child’s prayer.
What powers do they have? Whatever their child attributed to them through play. Can they gain new powers? If a child plays with them again, probably. The adults in their life are the parents, guardians, etc. of the child and anyone else nearby. In the case of the Outsider, there might be a whole secret world of animated toys to interact with.
The villainous version is a neglected or damaged toy, who just wants to be played with by someone - anyone - and will do whatever it takes to make it happen.
A very silly Nova character: Letter-man. Instead of burn, you hold 1-3 letters chosen from a bag of Scrabble tiles or something. You can use it to warp reality, e.g. using a T to turn a plane into a plant, or an L to turn the getaway car’s tires into tiles.
I feel the “power out of control” part of the Nova experience would come out when you had limited letters and started getting desperate… or weird. Maybe the bank robbers are getting away, and all you can think is turning the money into a Monet.