There is a way to play "offensively" or "aggressively," but it relies on the randomness of the level select. Use the warp zone to go to levels with annoying enemies (hammer bros, lakitus, spinies, flying cheep-cheeps, bowsers, and bloopers) and kill those bad guys like crazy to send them against opponents. Once they're introduced into the mix, players start dying off faster. Of course, all these enemies can come back to haunt you of course. Not an active form of offensive play, but it does make things harder for others.