The musical Final Fantasy game will have co-operative modes to participate in.
http://www.nintendoworldreport.com/news/29191
Theatrhythm: Final Fantasy will offer a multiplayer mode for up to three other players when it is released.
Four players will be able to take on several boss characters from across the series in a new mode called Chaos Temple, where players will be able to discover rare items and gain experience, all while the Song of Darkness plays throughout. Some of these bosses include Omega, Shinryu, and Ultima Weapon.
Theatrhythm: Final Fantasy is set to be released in Japan on February 16. No date for North America and Europe has yet been confirmed.