Knock, knock! It's Knuckles! And unlike Sonic he doesn't chuckle! He'd rather flex his muscles! Knuckles is Sonic's close rival and best friend, after being duped by Eggman form his first encounter with Sonic back in Angel Island, he has become a close ally of Sonic... unless he gets duped by Eggman again... In this game, he finds that Infinite is back once again and has taken the Master Emerald causing Angel Island to fall again! After crossing paths with Sonic and his new allies, he joins the Heroes of Smash after finding out that they have a common enemy and will do anything to make sure that the Master Emerald is safe once again.

Has a slightly gruffer voice than Sonic's, can get angry easily but cool headed when things are looking good.