Yes, you can do this. But remember: The more you do directly in ZBrush the more points you’ll get from the judging panel.
It does not have to be powers that have never been seen before. It must be characters that have never been seen before. The character as a whole.
Well, the contest is an exercise in anatomical accuracy. If you can find a way to accomplish that with a cartoon-like style you’re welcome to go for it. But you’ll also risk being seen by the judges as possibly trying to get around the rules. Whatever you do, make it believable.
Your initial post MUST include a concept sketch. Future posts may include sketches for various elements as well.