I don't care for fight scenes. They are meant to elicit adrenaline, but they just don't do it for me. Even if they did, I'd take thought provoking over adrenaline. And it sounds like the main point of the story is this fight? I don't even like the WWE. Unless it's somehow really, really, really clever I would pass. But it gives me an interesting idea. Somebody goes back in time and gets... say, Napoleon and brings him here to fight in a ring with some boxer. Meanwhile all of history is altered! I like historical fiction. If you made it about the world & what it would be like if so-and-so was taken out of history in order to fight in a match, I'd read it.
I just solved the Timeline Altering Problem(you know if you actually wanted to go into that kind of detail) See you should go with the idea of a multiverse. Going back in time and taking historical figures, or anyone, in this Universe is strictly forbidden. Any attempts is punishable by death or being shot into the sun. I dunno. However taking Al Capone from a different Universe is completely fine. Because who gives a crap about that Universe and whether or not it fraks up their own timeline?
Yeh I like the idea, but it would kinda ruin our history xD You would have to rewrite our history I guess.