Without crew and a very basic 3vs3 blacktop mode, the only mode that is left in 2k13 where we can play on the same team with friends online is Team-Up.
I really hope 2k made some improvements to this mode since there were so many problems and issues with it last year.
Also I really hope in 2k13 they finally add the Classic teams to private Team-Up, so we can have the ability to play with them online with/against our friends. It would be alot of fun being able to play Classic teams online against other Classic teams or even Current teams. That would sure make Team-Up alot more fun to play with our friends.