1. Juggernaut mode, and or the ability to apply special melee options to individual characters. Like one giant character on fire against three bunny-hooded players. (I don't know if anyone is unclear on the meaning of "juggernaut" but basically for brawl it'd mean that the 1st player to get a KO would be endowed with some special power, like giant size, or metal status or something, with the other players possibly getting a downgrade like Lip's flower. There would be a point limit with points only being garnered by KOing as the juggernaut or KOing the juggernaut - thus becoming it.)
2. Individual target levels. When I first saw the only 5 target levels update it crushed me. This is my ONLY disappointment so far with Brawl. The old target levels were customed tailored to each character's skills and moves to teach you how to use them better!
3. Online tournament mode. Since Sakurai refuses to have rankings, this would be a perfect way to satisfy people's need to fight worthy opponents on a regular basis while simultaneously keeping less experienced players from neccesarily having to always go against the cream of the crop. Plus it would satisfy a LOT of egos and knock even more down a peg. Do I even have to mention the incredible matches that would occur in the touney's final match? Now imagine that this match is being watched by hundreds of spectators and try not to drool on your keyboard.
4. Ganondorf with that flipping sword of his. I know I wasn't the only one who felt like he was being taunted when ganondorf waved his huge sword around after winning a match in melee!!! And now the one they gave him in twilight is even cooler! I want the King of evil to be armed, or at least have sword related special attacks.
5. Single player and Coop Boss Rush. I can honestly say that I truly expect nothing but the best from Brawl. Therefore it stands to reason that the Subspace Emissary will have a wealth of the most satisfying boss battles imagineable, and thusly may have the makings of the first boss rush mode I've ever actually cared about. Because we all know that playing through the same story mode over and over can get old just slightly faster than a good old fashioned throwdown. But again...this is assuming that the boss fights are sensational and warrant being set appart from the full story. *COUGH*Ridley*COUGH*