It would be aimed a lot more at beginners than people who already know the game (they should already know how to pick teams). I think some people would find it a lot easier to simply answer questions about how they want to play and have some options laid out for them automatically rather than having to digest a bunch of information first and then make decisions.
I would probably have it ask a series of questions aimed at narrowing down the player's preferences for a point character (zoning, heavy/grappler, Marvel character, Capcom character), and then have pre-stored data on tap for the kind of assists/DHC's that would build synergy with that character. I was thinking of displaying a variety of character attributes to pick from, and then narrow down the available attributes based on what can be found in a single character. The original idea came from the sense I get from Marvel that each character is special because they possess a unique distribution of basic abilities available to characters in the game (air dashes, armored moves, projectiles, etc.). So it's almost like being able to customize a character with the abilities that you want from them, and then a character already in the game would fit your customization.
Dunno. It would be a lot of work, and I probably will never end up doing it, but it just seemed like it could be a fun project.