Play as Amakusa Shiro Tokisada (Samurai Shodown 1)

Beat story mode using any character and save the game. Now on the character selection screen, enter versus mode, highlight the "?", then hold L1 + L2 + R1 + R2 and press Start.

Bonus options (Samurai Shodown 1)

Beat story mode using any character and save the game. Now on the main menu, enter versus mode, highlight the "Option" selection, then hold L1 + L2 + R1 + R2 and press Start.

Play as Kuroko or Mizuki (Samurai Shodown 2)

Select versus mode. Then at the character selection screen, press L1 + L2 + R1 + R2. Now move to the right to play as Mizuki or to the left to play as Kuroko.