Successfully complete the indicated task to unlock the corresponding character. 
Note: To unlock all characters easier, set the difficulty to the easiest with 
one round.

  Akuma (Gouki): After unlocking all characters except for Akuma, Gouken, and 
  Seth, play Arcade mode with any character you have already completed the game 
  with and the rounds set to one. Get at least one "Perfect" victory, and do not 
  lose a single round to fight Akuma after defeating Seth. Defeat Akuma to 
  unlock him.
  Cammy: Successfully complete Arcade mode with Crimson Viper.
  Dan: Successfully complete Arcade mode with Sakura.
  Fei Long: Successfully complete Arcade mode with Abel.
  Gen: Successfully complete Arcade mode with Chun-Li.
  Gouken: Successfully complete Arcade mode with Akuma (Gouki). Then, play 
  Arcade mode with any character you have already completed the game with and 
  the rounds set to one. Get at least one "Perfect" victory, three "Ultra" combo 
  finishes, five "First Attack" hits, and do not lose a single round to fight 
  Gouken after defeating Seth. Defeat Gouken to unlock him.
  Rose: Successfully complete Arcade mode with M. Bison.
  Sakura: Successfully complete Arcade mode with Ryu.
  Seth: Successfully complete Arcade mode with all characters, including the 
  bonus characters.