Sonic is ranked 18th on the tier list. Sonic is one of the fastest characters in the game, with his high movement and attack speed giving him a strong rushdown game. Sonic can use his Spin Dash to approach whilst dealing damage, and he has some decent finishers. He can use his Spin Kick to overwhelm his opponent, then KO them with his Flash Kick. This makes Sonic one of the better beginner characters to begin with.
However, Sonic has range problems, which gives him a very difficult time against characters that out range him. He is also totally incapable of handling projectiles, as he lacks a projectile himself. Sonic's movement speed actually works against him, as the game's physics make him very hard to control. Sonic lacks survivability, as his jump height is only average at best, he cannot momentum cancel, and he has a difficult time countering opponents' edgeguards. These traits give him bad match ups with higher tiered characters such as Lloyd and Tails.
Sonic is ranked one place below Super Sonic as the latter is much faster and has better finishers than Sonic, despite a slower attack speed and a larger hurtbox. This makes Sonic pretty much obsolete in the convoluted environment of SSF.
Sonic performs a windmill kick as it propels himself forward; this attack offers momentum-cancel, aiding in Sonic's survivability when launched off the stage. Though the distance covered is not that great, it still aids in Sonic's horizontal recovery.
Sonic uses the Spin Dash, he curls into a ball and propels forward at high speed, travelling a fixed distance. Keeping the attack button pressed causes Sonic to continuously roll forward, which reduces Sonic's damage hitbox window for the moment he is attacking, making him seemingly impervious to many attacks except projectiles. It also offers momentum-canceling properties, which increases Sonic's survivability a lot.