Defeat the Middle Boss (Geese or Bison/Vega).
Achieve at least one Finest KO.
Custom Grooves:
The Custom Groove option appears once a normal Boss has been defeated (normal Gouki or Rugal). Normal Bosses appear by fulfilling two of the four following conditions. Achieve over 1000 GPS by the end of the game.
Achieve four or more special KOs.
Middle Boss has appeared.
Achieve two or more LV3 super combo KOs.
Random Groove:
Press Start at the Groove selection screen.
The CPU has not made over six "first attacks".
The CPU has not made three or more Special KOs.
Victory quotes:
Hold Start + FP after winning a stage to make your character say an opponent specific quote. Hold Start + FK to make the character talk with a team member.