Successfully complete Street Fighter 3 or Street Fighter 3 Second Impact under any difficulty setting. Highlight Sean at the character selection screen and press Up, Up.
Fight as Gouki (Akuma)
Highlight Sean at the Street Fighter 3 Second Impact character selection screen and press Up.
Fight as Yang
Highlight Yun at the Street Fighter 3 character selection screen and press any Kick button.
Play as shin akuma
You got to get 3 perfects or more and then beat gill with each round with a super move. Then you fight akuma and you have to beat him the same way.
Fight as Gill...