EA Sports MMA online features:
Belt race: Core matchmaking mode, fight players of similar skill level online, start as white belt and earn XP to progress your character through 45 belt levels (followed by another 45 “master” levels for high skilled players), earn opportunities to fight for Strikeforce belts, earn championship belts in each of the weight classes.
Fight cards: Act as the fight promoter, build fight cards to put on a night of fights with your friends, up to 8 spectators can watch and commentate through their headsets while fights are played
Fight replays: Full fights can be saved for public viewing on the leaderboards and by your friends, save and upload fight highlights to share with friends on EASportsMMA.com
Fighter share: Share your created career mode fighters online, organized by top ranked, most downloaded, most recent, friends’ fighters, also bookmark fighters on EASportsMMA.com to find again on console. (If the community embraces this, I imagine you’ll be able to find any created UFC fighter you want in due time)
Online profile: Manage your profile online at EASportsMMA.com, keep track of your stats, record, leaderboard positions, online belts, Strikeforce championship status, shared fighters, store your hype and highlight videos
Online content: Blogs from EA Sports fight promoters, info on upcoming EA Sports Live Broadcasts, tips and tricks, Live Broadcasts streamed live and archived on the web, live chats with community managers
IGN has more details on the different modes.