I say no you can't ban plays. If you are in a league you should set up a set of rules for fair play. EXAMPLE: A league I was in from a different game banned the flea flicker because it's a cheap easy play. That is all you have to do. As far as online goes you just have to tighten up your defense.
When I play Madden 09 online I have a certain set of plays, 10 passing and 6 running, that I always start my game off with. Some plays seem to work more then others, but usually my opponent can figure out what I'm up to if I do not mix it up as the game progresses.
A play that one person feels should be banned another may not, who's to decide? This is a can of worms that should not be opened.