This gen we have seen many cross over games. Some were fighters like street fighter x tekken. Some were crossovers within the same series like final fantasy theatrythm. Others were srpgs like cross edge, project x zone, pokemon conquest. Others were even board games mixing dragon quest characters with Nintendo characters.
With the recent announcement of the latest cross over to blitzkrieg japan, Fire Emblem X Shin Megami Tensei. I thought it might be interesting to think about other cross overs that might work or be potentially interesting.
Disgaea X Mugen Soul - Disgaea is an srpg. Mugel Soul is a classic rpg whose main source of influence was disgaea. I thought putting the two together would be a match made in heaven. In my mind this would be an srpg mega insanity crossover maybe even having neptunia characters as well.
Nintendo Smash Bros SRPG - Why hasn't this happened yet? Seriously? Put Intelligent Systems in charge of this after they finish Fire emblem X SMT, then make every character that's ever been in Smash a sprite and let them duke it out rpg style on a grid.
Digimon X Pokemon - This is more of a fanboy delusion than anything else. I would love to see a combination of the digimon story DS titles (Evolution Depth, Monster Variety) with main line pokemon games (online, modes, the rabbid teen following) rapped up in a neat package.
The real question is, what cross overs would you like to see down the road?