I think everyone is gonna want the same things out of this game and even though most of what I want has already been said I'll add my wish list.
First thing of course I hope they have a great control system and tons of moves you can do. Look at games like Tekken Tag. They have a ton of characters and each character has tons of moves that are unique to that character. Of course just tapping one button would do a simple jab or kick, but make it more difficult to perform the signature moves and more powerful moves so there is more skill to the game rather than just button mashing your way to the win.
I hope they have a lot of fighters to choose from at the start of the game. I don't mind unlocking fighters or even paying for a download as long as your getting lots of fighters in the download.
I would like the ability to set up my own fight cards and be able to choose to just watch the events if I like.
As far as online goes I think that no matter what fighter you choose you should start out with an 0-0 record so you can work your way up the rankings. I hope they have online tournaments.
I'm hoping they make it so the fighters don't grab the fence lol and I hope they make it so the refs don't stop the fights to early.
In the end I just hope they get the controls down, lots of fighters and a good ranking system for online.