Have you watched The Law of Ueki? If you haven't, I definitely recommend you read and watch it. What is Ueki? or better ask.. Who is Ueki?
Kousuke Ueki is a regular middle school student who was picked by a God candidate, Koba-sen, to participate in a competition where the picked will compete against each other and will try to win against other picked juniors and will serve as the God candidates' fighters.
The God candidate will win together with his last standing fighter. To be able to fight, the God candidate must entitle the fighter or the junior student that was picked with a unique power which can only be used against other fighters or to normal people and be punished by...[I don't want to spoil a lot of things you see..] The winning God Candidate will become The New God of Heaven and the winning fighter will receive the Blank Zai (or talent), a talent that can be anything they choose.