It was recently revealed that a new crossover game by three very big developers (Capcom, Namco Bandai and Sega) is in development for the 3DS.

Titled Project X Zone, with the “X” being pronounced as “cross,” popular characters from each developer will be brought together to create a new strategy RPG. A current list has been revealed with the characters, also revealing they will operate in pairs:

Kos-Mos and T-elos (Xenosaga)
Yurie and Estel (Tales of Vesperia)
Kaito and Black Rose (.hack)
Ryu & Ken (Street Fighter 0)
X and Zero (Mega Man)
Demitri and Dante (Darkstalkers, Devil May Cry)
Ulala and Touma (Space Channel 5, Shining Force EXA)
Sanger Somvold (Super Robot Wars)
Jin and Ling Xiaoyu (Tekken)
Chris and Jill (Resident Evil)
Shinguji Sakura and Ogami Ichiro (Sakura Wars)
Pai and Akira (Virtua Fighter)
Kurt and Riela (Valkyria Chronicles)

Kensuke Tsukanaka, from Namco, told Famitsu that while this list is not complete and is open to change, each character will use their own unique moveset from their traditional games.
He also revealed that hidden characters will be put in the game and each character will bring an individual flavour to the game, even though some of them may be believed to not work well in a game such as this.

The game is reportedly 50% complete, with an aimed release date of 2012 in Japan. An international release date has not been confirmed.