Air Boarder 64
Complete the following to open up bonus characters:
Earn an "A" rank on each level and track in "Street Work" mode.
Earn a "S" rank on each level and track in "Street Work" mode.
Complete each level and track in "Time Attack" mode within the time limit.
Earn a "Perfect" rank on each level and track in "Coin" mode.
Unlock all four bonus characters. Then at the board selection screen, press Up, Up, Down, Down, Left, Right, Left, Right, B, A. This will open up the Ika-Chu, Father, J-B, and J-Arm boards.
Thanks to Revolution readers Ernie Rodriguez and Christian Slydahl!