Online Mode:
Simple Match - Basically quick match, you can set amount of rounds and region
Rank Match - set amount of rounds, region, and opponent strength max/min
Lobby Match - round, region, opponent strength, fight rules and fight type, up to 16 players
Leader Boards - you can download replays here
Fighter List - Rival System like SCV. If you view them as a rival after your match, it gives you stats on your win/loss ratio against them. You can also send them throwdowns or invites to your game. Also able to remove them if you want.
When you search or create your lobby, hover over fight rules and you will be given these options: Winner stays, Loser Stays, Tournament, kumite, and online dojo. In fight type, there's solo and tag fight. Haven't found any tag rooms with 2 players in one team atm so I'm not sure. When you're in Arcade, Time Attack and Survival mode, an icon will appear in the bottom right letting you know you have a challenger who is waiting to play with you. You could either choose to ignore it and will disappear shortly or you could select it and you will be able to play that opponent (you have no clue who you are playing until you join their room). I am trouble connecting through players from Throwdown as of now, but i'm hoping to see that dissolve once the game officially comes