Starting on December 16, you can dress the three Tales of Graces girls with Idolm@ster: Dearly Stars outfits.
Sophie, Cheria, and Pascal dress as Eri, Ryo, and Ai respectively. Costumes are active during battle and cutscenes. Here’s an example of an event where everyone is wearing their normal outfits…
… and the same scene with Idolma@ster cosplay.
Each costume is locked to a specific character (no, you can’t dress Asbel like Ryo) and costs 400 Wii Points ($4). Purchase all of them and the girls do a special battle winning pose.