Dr. Mario 64 cheats and cheat codes for Nintendo 64

Unlock Metal Mario in VS mode:
Finish the story mode with Wario in normal, hard, or super hard modes
without losing once. Then, beat Rudy, after beat Metal Mario also without
losing.

Unlock Vampire Wario in VS mode:
Finish the story mode with Dr. Mario in normal, hard, or super hard modes
without losing once. Then, beat Rudy, after beat Vampire Wario also without
losing.

Enable S.Hard mode:
Go to story mode and highlight the "Hard" option.
Hit Z to change the difficulty level.

Increase the computer AI of character one star to Hard:
Go to the character selection screen in VS mode, and highlight a character
Hold L and press A.

Increase the computer AI of character two stars to S.Hard:
Go to the character selection screen in VS mode, and highlight a character
Hold L and press B.