Ahh yes... Capcom vs. SNK 2. I have the first one, and I think it's a very good game, although not nearly as polished as the typical Capcom fighter. I think I side with the majority when I say it's a good game but should (and definitely could) be better. It seems Capcom was in a rush to get it out, which is very atypical of them. The most notable problem is easily the use of the SFA sprites.
For the sequel, I'd like to see:
* New Sprites for ALL Capcom characters.
* Definitely, a wider selection of Capcom characters. CvS is ALL Street Fighter except for Morrigan (my all-time fav. character). More Vampire characters, and some others could include Jin, Strider, Megaman, Captain Commando, and Jill Valentine. That would be sweet! Also, Lilith would make a good hidden character. I think a lot of people would like to see her again, and if there is a new Morrigan sprite, why not?
* The SNK roster, to a lesser extent, could also include a wider variety. I think everyone wants to see Andy Bogard and Leona, but wouldn't it be cool to have more characters from Samurai Shodown? Implementing SS chars. would be a challenge, being weapons-based. What about Metal Slug characters, or some others?
* 3D stages ala Marvel vs. Capcom 2. I didn't think it would work either, but the stages in that game are incredible.
* As much as I think the ratio system is a good idea, I'd have to say that I like it more when everyone is on equal grounds. Using Ratio 1 characters just sucks. There should be an option to have it on or turn it off completely (not just ratio select).
* More rivalries, along with special opening animations. The first game seems to be sorely lacking.
* The Groove Selection should remain intact. It's a very good idea.
* Do away with EX characters. They just complicate everything, but Evil Ryu, Riot of the Blood Iori, and Akuma should remain as hidden bosses though.
* A feature to make your own custom teams, with music and team name edit, as seen in Match of the Millenium. Nice.
* Stages that change accoring to the time of day, ala some SNK fighting games. This ups the replay value.
* A FINISHED game! It shouldn't be released until it is done. I want to see at least 40 characters!
Hope Capcom is watching...