I've only briefly played online (my connection isn't great so I don't think I'll be able to make a habit of it), but I would suggest giving these a shot:
For example whats the best D to cut off the Pg who constantly drive the Baseline !!
Man-to-Man, but let your CPU teammate guard him. Control one of your big men, and if your point guard is beaten off the dribble, move over to block or contest the shot.
Or the Center or the Pf who uses the 2 ft Shot ( which i might add is unstoppable even though people say certain zones work it does not though)
Double team, same as you would if you were playing a CPU opponent. You may want to do this automatically (ie calling for a double team using QuickPlays) or you may want to let a CPU teammate guard the opponent's PF or C, while you control one of your guards. Move in and either make him pick up his dribble, or swipe at the ball to knock it loose (and hopefully pick it up for a steal).
Or the 3pt shot Abusers
Man-to-Man D, contesting every shot. Assuming you're not playing in a league with tight rules, you might want to play some of your guys out of position or at their secondary position to shut down players who are lighting you up.
Last but not least the Prolific Pro-Hopper
The best I can offer is to control a big man and go for the block every time.
Hope this helps.
