Excitebike 64

Display cheat menu:
Go to the main menu and press the following button combination:
Hold L + C-Right + C-Down and hit A.
After enter any of the following cheat
codes at the cheat screen.

Unlock all stunts: Enter "TRICKSTER"
Stunt bonus: Enter "SHOWOFF"
Invincibility mode: Enter "MOWER"
Riders become Invisible: Enter "INVISRIDER"
Rider become transparent: Enter "XLURIDER"
Downhill race mode: Enter "WHEEEEEEEE"
Debug mode: Enter "IMGOINGNOW"
Giant head mode: Enter "BLAHBLAH"
Tiny head mode: Enter "PINHEAD"
Mirror mode: Enter "YADAYADA"
Night mode: Enter "MIDNIGHT"
Strange colors: Enter "ROTCOLS"
Beat This! mode: Enter "PATWELLS"
Dev-team image: Enter "UGLYMUGS"

Original NES Excitebike at "Special Tracks" menu:
Finish tutorial mode once

Unlock Soccer mode:
Win 1st place in the silver round of the novice season

Unlock Hill climb mode:
Win 1st place in the gold round of the amateur season

Unlock Excite 3D mode:
Win 1st place in the challenge round of the pro season