Fight as Bosses:
Press C(6), B(3), C(4) at the character selection screen to access Musashi, Kagami-N, and Kagami-H.

Alternate costumes:
Highlight a fighter and press D or Start at the character selection screen.

Hint: Lee: Defeating Kagemi:
When near standing Kagemi, hold Forward and press A.

Hint: Freeze:
As Yuki, Amano, Akari, Moriya, Musashi and Kagemi, hold A + B on controller two.