Mecha Sonic is a powerful robot built by Doctor Eggman that appeared in the game Sonic & Knuckles. He attacks both Sonic the Hedgehog and Knuckles the Echidna, and appears in the Sky Sanctuary Zone in four separate boss battles across the two storylines of the game (three times for Sonic and once against Knuckles). He stands 130 cm and weighs 170 kg. His abilities are hyper jet boosters, teleportation and laser blasts.
Mecha Sonic first appears as an enemy of Sonic (and possibly Tails, if playing Sonic 3 & Knuckles). He appears three times. In the first two appearances, he is piloting Doctor Eggman’s Egg Mobile, first with an attached checker-ball weight (as Eggman did in the Green Hill Zone in Sonic the Hedgehog) then surrounded by swirling orbs (as Eggman did in the Metropolis Zone in Sonic the Hedgehog 2). In its third battle against Sonic, it appears on foot, and the two fight hand-to-hand.
Although Sonic defeats his Mecha counterpart, the robot is shown to survive the battle. It reappears in Knuckles’ story as the final boss of the game. First Knuckles defeats it in a simple one-on-one fight (as Sonic did). Then Mecha Sonic flees to the Master Emerald, which it uses to power itself up into an invincible, glowing, golden form (referred to as Super Mecha Sonic, after its resemblance to Super Sonic). In this form it is untouchable, but Knuckles is able to defeat it by striking when its power runs out and it is forced to go back to the Master Emerald for a recharge. When Knuckles defeats the robot this time, it explodes.