On top of the Star Driver collaboration, Namco Bandai has an Idolm@ster crossover in Tales of Xillia. Millia, Leia, and Elise (but not Tipo) have Idolm@ster 2 costumes.
Millia is dressed as Shijou Takane, Leia is Hibiki Ganaha, and Elise is Harkua Amani.
All three costumes will be paid downloadable content, but Namco Bandai have not announced a price or distribution date. Tales of Xillia comes out on September 8 in Japan.
Namco Bandai also released this video of the game’s shop system. Stores in Tales of Xillia level up when you buy items. You can speed up growth by bringing specific materials back to stores.