Initially, only Sonic and Tails are available as playable characters. However, as you progress through the main story, you'll unlock additional characters, each with their unique abilities that significantly expand your gameplay options and open up new pathways in previous zones. Unlocking all characters is essential for experiencing the full depth of the tag-team system.
- Knuckles the Echidna: Unlocked after completing Route 99 and defeating the Eggman Robo boss. Knuckles can glide and climb walls, making him excellent for vertical exploration and finding shortcuts.
- Amy Rose: Unlocked after completing Sunset Hill and defeating the Egg Hammer 3 boss. Amy wields her Piko Piko Hammer for powerful ground attacks and a high jump, useful for clearing groups of enemies and reaching higher platforms.
- Cream the Rabbit: Unlocked after completing Ocean Base and defeating the Egg Saucer boss. Cream can fly with Cheese the Chao, similar to Tails, and Cheese can attack enemies, providing excellent aerial mobility and offensive support.
Once a character is unlocked, they become available for selection in the character select screen before starting any zone. Replaying earlier zones with newly unlocked characters can reveal previously inaccessible areas or make achieving 'A' ranks much easier due to their unique abilities. Experiment with different leader/partner combinations to discover powerful synergies.