I seen this game in Dwayne's forum. And I think that I could bring it to wiki.
Don't know how to play? It's simple, you choose two Ben 10 characters, and say: Character Number 1 vs. Character Number 2
Other user will awnser with his opinion, and suggest a new battle, the next one will suggest another, etc.
My battle:
Spidermonkey vs. Four Arms
Good game. And sorry for the english, I gave my best.