Thing is, I don't even have to tell my friends what to do in Gears. We have a specific strategy and talk sports, crack jokes, etc. while playing. I'm sure the same goes for CoD and whatever other game you can think of that supports multiple players. How did we get to that point? It surely wasn't being Gears savants, mind you, it was practice. A co-op fighting game would be just as easy and fun to master with another person as a co-op shooter--and just as hectic and goofy in the interim. After a few weeks of practice, it would become second nature, just like anything else on the market. As stated, a lot of the "better than you" types would likely protest this mode simply because A) they don't want anyone they know getting better than them at the game, and B) they may not have many friends to begin with due to their attitude, but why should we let a pool of a hundred or so players ruin the fun for the rest of us?
In another light, it could also balance out teams. I can't be the only decent MK player with dozens of friends who are just plain bad at the game. They want to have fun without feeling inept at the game, so this is another way to allow them to get together with pals and play a game they really like but can't for the life of them get good at it.
I've seen swap-out tag-team tournaments before with Killer Instinct, they were a blast. They would be a lot more fluid than four guys hovering around an arcade cabinet. This could not only work, it could be fun in a whole new light that we've never seen with MK in the past. I dig it.