Rave Master

Unlock Gale: Finish Story Mode with Shuda.
Unlock Sieg Hart: Finish Story Mode with Go.
Unlock King: Finish Story Mode with Haru.
Unlock Pasha: Finish Story Mode with Elie.
Unlock Read Admiral: Finish Story Mode with Musica.

Unlock Reina
Hit Up, Up, Down, Down, Left, Right, Left, Right, B, A at the title screen.

Unlock Beast King
Beat Story Mode with Haru on hard mode without using a single continue.
After round 7 King will change to a Beast. Defeat him.

Change costumes
Finish 1 On 3 mode in hard mode with Elie, Haru, or Musica

Unlock 1 On 2 Free mode
Finish all storylines in story mode

Unlock 1 On 3 Free mode
Unlock all bonus characters and Finish Free mode with them

Unlock Outlaw
Finish the story mode with everyone to unlock VS 2 enemies at once in
Free mode. After choose Rear Admiral in Free Mode and set it to 1 on 2
with dificulty set to Hard. After you beat it, you will have unlocked Outlaw.