Boss Battle Mode
First unlock Shin Akuma and Ultimate Rugal. Then to play Boss Battle Mode, hold Triangle and Square while selecting Arcade Mode and your Groove.
Extra options
To unlock extra options, complete the Boss battle mode. To access the extra options, go to the options menu. In this section you'll be able to toggle such cheats like character invincible and infinite gauge.
Fight Shin Akuma and Ultimate Rugal
to fight against one of the two characters as the boss, you must meet these three conditions
Get 1500 points by the time you beat the final fight
Get a Dramatic KO in any one round
Fight and defeat the miniboss
If you're using a SNK groove you'll fight against Akuma, if you'r usign a Capcin groove, you'll fight Rugal.
Groove Edit Mode
To unlock groove edit mode, defeat either Rugal or Akuma in Arcade Mode. This will be accessible from the main menu. In Groove Edit Mode, you can customize two of your own Grooves and save them to use in battle.
Infinite Edit Groove Points
To get infinite groove mode point, complete All Battle Survival Mode.You'll be able to save EX Groove that uses more than 4000 points.
Unlock Shin Akuma and Ultimate Rugal
To unlock Shin Akuma or Ultimate Rugal defeat either in arcade mode to have that character playable.