Dr. Mario 64 Cheats

To open up S-Hard difficulty in Story mode, highlight Hard and press the Z button. Pressing the Z button again switches it back to Hard.

To get more Viruses, Press L or R in marathon mode to increase the number of viruses.

When selecting a computer opponent in Vs. Computer mode, hold the L button and press A to make his difficulty one star harder (the equivalent of Hard level).

By holding L and pressing B, the computer player's difficulty increases two stars (the equivalent of S-Hard level).