Uh... the KOF system of strikers is different from the MvC2 system of strikers. In KOF you designate strikers based on the team you choose while in MvC2 either of the two inactive partners can be strikers or you can switch to them. Strikers in KOF cost strike bombs or super bar while in MvC2 they don't cost anything.
As for tag, this would mean changing the six buttons to a MvC2 style layout, which I am against. Also, with a Capcom tag game comes assists, delayed supers, team supers, triple-team attacks, insane 200-hit air combos, and the like. Not good, but I'd like to see SNK characters in a tag game.
About predetermined team groupings, this would be somewhat difficult, as SNK groups characters in fours for KOF and Capcom groups characters in twos for Dramatic Battle in SFA3, or twos/threes in tag games.
And it would be hard to group the Alpha characters in fours (partly because there are 35 characters in A3 for GBA). Examples
- Someone would have to accompany the team of Charlie, Guile, and Chun-Li
- Someone like Bison could fit in either a team of Balrog, Vega, Sagat, or a team of Cammy, Juli, Juni
- By grouping teams from games like they do in KOF, some groupings make no sense... Example: four out of Guy, Cody, Maki, Sodom, and Rolento. In the storyline, you wouldn't be able to get the first three to cooperate with the last two.