"Any order you assign us master, it is my job to help you lead forward to your goal"-Metal Knuckles to Spartan Gerald
Metal Knuckles is the secondary antagonist of Super Smash Bros. Brawl Crossover. He is the robotic creation of Knuckles The Echidna where unlike Metal Sonic, Metal Knuckles wasn't created by Dr. Eggman and was instead created by the Forerunners, he later joins and becomes the second in command of Clark Thornton's gang. He is also the arch enemy of Emerl whom allies with Spartan Joaquin's team and Clark's best friend.
As he is usually ruthless and arrogant, Metal Knuckle behaves more aggressive, violent, cold-blooded, and intelligent than Metal Sonic. He seems to be stubborn and selfish refusing to obey with people that consider him a minion or pawn as he rebelled against the Forerunners stating he doesn't take orders when 343 Guilty Spark once assigned him to a minion of the Forerunners, defeat Knuckles the Echidna, and destroy or imprison the echidnas. However unlike Knuckles who is gullible always being deceived, Metal Knuckles is suspicious never getting fooled by someone who tries to trick him.