I'd like to see as many as possible. It'd really disappoint me if we got very few characters or more third party characters when there are so many ps1, 2 and 3 characters. Obviously they might not release certain characters as to not "run out of ideas" for sequels and such.
for the games they are doing I'd like to see at least 2 characters (preferrably 1 good and 1 bad) from each.
Let me throw this out there. Making lots of DLC to extend the franchises life is economically better then making a new game. If SuperBot made a sequel, they would probably want a new/updated game engine which would take a lot of time and money to produce, and they have to make sure to develop a bunch of new fractures so the sequel wont seem like a rip of the first one. Now think about everything that goes into the games you buy from gamestop or amazon etc. That's about $4-$6 dollar per game (Proof), not including how much Sony spends on shipping the game all around the world.
Compare that to the price of hosting files on a server for people to access. It doesn't make sense to make equals every year. That's why we should have a library of 50 or so characters. Then 3 years later, a new game comes out with new loved characters in the video game world, and they bring the old characters back with DLC and call them classic characters. And hell, if Nintendo made it so, I'd pay $5 for Mewtwo, Banjo, Roy, and Pichu to be Brawl, because I loved them in melee