Play as Adversa
     At  the  player select screen, press Down, L1, R2, Up, Square, X.
If done correctly, you will hear a ball bounce.

Play as Mattox
     Go  to  the  Mode  Select  screen and choose Match. At the player
select  screen,  press  L2,  L2, R1, R1, R1, Down, Triangle, Triangle,
Triangle, Triangle, X. If done correctly, you will hear a ball bounce.