The following characters are unlocked by completing the indicated races in Cartoon Eliminator.

Unlock Flem:
Complete the races from Pork Butt challenge in Cartoon Eliminator.

Unlock Fuzzy Lumpkins and Him:
Complete the races from Townsville Tournament in Cartoon Eliminator.

Unlock Bunny Bravo:
Complete the races from Aron Man Challege in Cartoon Eliminator.

Unlock Eustace:
Complete the races from Cowardly Competion in Cartoon Eliminator.

Unlock Red Guy:
Complete the races from UR Challenged in Cartoon Eliminator.

Unlock Mom and Dad:
Complete the races from Super Science Tournament in Cartoon Eliminator.

At the 'Options' menu go to 'Nickname' screen and enter the following codes without the quotes to activate the corresponding effect. Using these codes will deactivate the option to save the game when they are in use.

Unlock Everything:
Enter 'GIMMIE'.

Unlock Top-Down View:
Enter 'IMACOPTER'.

Unlock Unlimited Dumb Rockets:
Enter 'ROCKETMAN'.

Unlock Unlimited Superpower Energy:
Enter 'SPINACH'.

Enables ALL Hazards and Pickups in Time Trial:
Enter 'AAARGH'.

Rockets turn Non-Invulnerable Opponents into Stone:
Enter 'STONEME'.

Unlock the following Cartoons for Gallery and Cartoon Themed tracks by completing the corresponding task.

Unlock I.M Weasel = 'Enemy Camp' and Track A:
Beat the 'U R Challenged Cup'.

Unlock C&C = 'Black Sheep Of The Family' and Track A:
Beat the 'Pork Butt Challenge'.

Unlock Johnny Bravo = 'Doommates' and Track A:
Beat the 'Aron Man Challenge'.

Unlock CTCD = 'Robot Randy' and Track A:
Beat the 'Cowardly Competition'.

Unlock PPG = 'Telephonies' and Track A:
Beat the 'Townsville Tournement'.

Unlock Dexter's Lab = 'Dexter's Rival' and Track A:
Beat the 'Super Science Tournement'.

Unlock I.M Weasel = 'My Friend, The Smart Banana' and Track B:
Beat the I.M Weasel Super Tournement.

Unlock Johnny Bravo = 'Johnny's Telethon' and Track B:
Beat the Johnny Bravo Super Tournement.

Unlock CTCD = 'The Magic Tree Of Nowhere' and Track B:
Beat the Courage the Cowardly Dog Super Tournement

Unlock C&C = 'Child Star' and Track B:
Beat the Cow and Chicken Super Tournement.

Unlock Dexter's Lab = 'Mandarker' and Track B:
Beat the Dexter's Laboratory Super Tournement.

Unlock PPG = 'Tough Love' and Track B:
Beat the Powerpuff Girls Super Tournement.