Samba de Amigo Ver. 2000 Codes -

Random mode:
Quickly shake Left Maraca Low fifteen times at the difficulty selection screen. Note: For the standard Dreamcast controller, hold the Down button.

Super hard mode:
Quickly shake Left Maraca High fifteen times at the difficulty selection screen. Note: For the standard Dreamcast controller, hold the Up button.

Survival mode:
Get a Maraca Star rank in challenge mode to unlock survival mode.