From Sonic - Wiki on Neoseeker

[edit] History

Cheese The Chao is a young, neutral Chao, who has yet to change into his adolescent form. (Neutral, Dark or hero)

It is easy to establish Cheese from other Chao because of the red bow-tie he wears.

He is Cream the Rabbit's best friend and is always seen with her.

Cheese's first appearance was in Sonic Advance 2 for the Game Boy Advance. In Sonic Advance 2, Sonic Advance 3 and Sonic Battle, Cheese is accompanied by Cream and is a method of attack. Cream points to an enemy, and Cheese charges forward and destroys or damages the enemy on contact. In Sonic Advance 3, Cheese has the unique ability to temporarily shape-shift into a Chao version of Sonic, Tails, Knuckles, or Amy upon being teamed with them.

He is also seen in the anime, Sonic X tagging along with Cream.