Within the Grand Prix mode, depending on which character you select you may see different CPUs than normal during the races. This is due to each character having a certain 'rival' assigned to them within the files. While early interviews suggest that this system was meant to become something more (e.g, your rival would be more aggressive to you during the race), currently it remains as nothing but determining which characters you'll face.

The CPUs most commonly seen within Grand Prix are Sonic, Tails, Shadow, Amy, Dr. Eggman, Big, AiAi and Amigo. In most cases, Sonic & Big are cut to make room for you and your rival, however one of the two or both may remain depending if your selected character or rival are within the lineup mentioned before (or if your character doesn't have a rival, in which case only Big is cut to make room for your character).

List of Rivals (For reference on how to read this list: Character Chosen - Rival Assigned)

• AiAi - Amigo
• Alex Kidd - Opa-Opa
• Amigo - Ulala
• Amy - Sonic
• B.D Joe - Beat
• Beat - B.D Joe
• Big - ChuChus
• Billy Hatcher - AiAi
• Bonanza Bros. - Zobio & Zobiko
• ChuChus - Big
• Dr. Eggman - Sonic
• Jacky & Akira - Ryo
• Knuckles - Dr. Eggman
• Opa-Opa - Alex Kidd
• Ryo/Ryo (Forklift) - Jacky & Akira
• Shadow - Sonic
• Sonic - Dr. Eggman
• Tails - Dr. Eggman
• Ulala - ChuChus
• Zobio & Zobiko - Bonanza Bros.

Banjo & Kazooie, Avatar, Mii, and Metal Sonic do not have rivals.