That's the whole point of this game: to answer questions like these. Of course, it's going to be a challenge to maintain game balance for a project of this magnitude, but hey, that's what subscriptions and micropayments are for. We could sell branded merchandize that players could use to accessorize their fighters (nothing that would break balance, mind you), and license "hot" celebrities that players can use in their battles.
Speaking of which, that brings up the whole notion of advancement. The game is predicated on balanced, point-based battles. What will motivate players to fight and win, apart from the sheer enjoyment of battle? Well, the model is pretty simple, and very enticing, in my opinion. First of all, the most successful players will top the leader boards, granting them adulation (and resentment) of their fellows. But more importantly, each victory will net you points, which, while it won't grant you access to fighters or accessories that are inherently more powerful, will allow you a greater variety to choose from. Newbs, for instance, can pick, say, the NYPD SWAT team, Aquaman, or a parliament of Spotted Owls. Meanwhile, highly ranked players can, in addition to the aforementioned, choose to fight as a Beholder from D&D, an army of 200 six year olds, or Hulk Hogan, age 29. That makes sense, right?

Beast Man from Masters of the Universe: 400 points, base value.
The best part is that players can change their configuration at any time. If you're tired of playing a Tron l light cycle piloted by Michael Knight, then feel free to cash in your points and start from scratch. Your name will be attached to whatever it is you choose to field, so you never risk losing your reputation.
I guess I'll leave you with what's, in my opinion, the game's most innovative element. In a nutshell, the game will play differently with each fighter type. If you're commanding a squad of Marines, Stormtroopers, or orcish warriors, then it'll play like Rainbow Six or Command & Conquer (your choice). If you're Rambo or the Master Chief, then it's an FPS. If you're a vehicle or a sports team, then, well, you can make the analogies. It doesn't matter what your opponent chooses. The game will render everything from your own fighter's point of view, and same with the opponent. If you think about it, it's pretty revolutionary. It's like every game ever made rolled into one.
Well, that's about all I can share with you right now. Again, I'd like to reiterate that I'm in no way trying to tolerate any clowns that want to be funny and steal my ideas. But by all means, if you want to approach me with a business proposition, then I'm all ears.