Unlock Hints:
Unlock Boss Challenge Mode: Unlock both Shin Akuma and Ultimate Rugal then go to Arcade mode and hold X + Y and press Start.
Unlock Custom Grooves: Beat the Normal Bosses (Akuma or Regal). To make a Normal Boss appear do any 2 of the following 4 things:
Get over 1000 GPS by the end of the game, Get four or more special KOs, Achieve two or more LV3 super combo KOs or get the Middle Boss to appear.
Unlock Extra Options: Beat all opponents in the Boss Challenge Mode.
Unlock Hidden Bosses: Perform 2 of the following 3 things to unlock a boss: Get over 1500 GPS by the end, defeat Geese or Bison/Vega, or get at least one Finest KO.
Note: If you play with a Capcom groove you will get Ultimate Rugal and if you play with a SNK groove you will get Shin Akuma.