All Working Konami Krazy Racers Cheats - GBA

Bear
Start a race on the Cyber Field 2 track. Collect the blue diamond between the two holes near the finish line. Complete the race and save the game. Bear will be unlocked on the character selection screen.

Ebisumaru
Unlock Bear. Play the Ganbare Dochu 1 and 2 tracks with Bear and beat the record time to unlock Ebisumaru.

Vic Viper
Start a race on the Moon Road track. Collect the Blue Bell power-up, then find the first long jump on the track. Jump and use the power-up for an extra boost to land on a long platform that has the blue diamond. Collect the blue diamond, complete the race, and save the game. Vic Viper will be unlocked on the character selection screen.

Quick start
Accelerate at the moment when the third light dims and fourth light illuminates.

Magma Castle 1: Shortcut
Cross the first two bridges and the first dirt path. On the second dirt path, instead of making a right to continue, go to the far left and you will find a jump that leads to another dirt path. Jump off the three small jumps, then make a sharp left turn. The finish line will be a few inches away from you.