i'm pretty good at MvC2 myself. I don't do infinites...but i think i can hold my own and get lucky enough for a win here or there in none-dead-serious play. I occasionally play people here that can do infinites, so i'm at least somewhat experienced with the farmiliarity of what to look out for settup wise, and the habits of top-tier play.
My best team is BlackHeart, Doom, Cyclopes. I do however pride myself in my lower tiers and prefer the more creative play required in using them: spidey, venom, amingo, collosus, and dhalsim being my favorites.
I play Ultimate Mortal Kombat 3 online, via mame32k on kaillera network..and that would probabl be my 2nd best fighter, actually. But classic MK players are few and far between..and its very rare for people to have the right system and game to meet up and play it. (although i suppose MK:Trilogy is close enough, despite many minute modifications that alter play almot more than most would think)