Everytime you beat the game in any difficulty, you unlock the original themes for the characters in that team. You can access them by going to the Options menu, and then to the Sound options.
After beating the game with all characters, including Shin Akuma , and Pyron, and beating Ingrid at least once in Arcade mode, you can play throgh Arcade mode with classic character themes.
Hold Square when selecting Arcade Mode.
Beat the game to unlock Pyron (boss) and his stage.
To fight Shin Akuma in Arcade mode, beat the game with the following:
-Win every round, including Pyron stage
-2-3 Perfects finish
-At least 1 super combo finish out of the 2 rounds
-Need to fight Ingrid
Difficulty doesnt matter, set to 1 star for easiest, Shin Akuma will challenge after you defeat Pryon. Defeating Shin Akuma unlocks him as a playable character and his stage. Using him to defeat Pyron subsequently will unlock his BGM from SSF2T
Before the match starts, hold 2 kick buttons until your second character is the first to fight in the first round.