Mecha Sonic (Sky Sanctuary Zone)



Mecha Sonic (メカソニック) 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 five separate boss battles across the two story lines of the game (three times against Sonic and twice against Knuckles). He can roll into a ball and spin-dash just like his living counterpart. He can also float as a spiky ball and attack from above.

History
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 his third and last battle against Sonic, he now appears on foot, and the two fight hand-to-hand.

Although Sonic defeats his Mecha counterpart, the robot is shown to survive the battle. He reappears in Knuckles' story as the final boss of the game. First, Knuckles defeats him in a simple one-on-one fight (as Sonic did). Then Mecha Sonic flees to the Master Emerald, which he uses to power himself up into an invincible, glowing, golden form (referred to as Super Mecha Sonic, after his resemblance to Super Sonic). In this form he is untouchable, and does damage to whoever touches it but Knuckles is able to defeat him by striking when his power runs out and he is forced to go back to the Master Emerald for a short recharge. When Knuckles defeats the robot this time, he explodes, this time defeated for good. However, his destruction also takes the remains of the Sky Sanctuary with him, Knuckles only barely escaping with Sonic's help, the latter piloting the Tornado.

Naming
This robot was not named in the English-language manuals accompanying Sonic & Knuckles, but in the Japanese strategy guide he was called "Mecha Sonic" (as were the Sonic robots in both versions of Sonic the Hedgehog 2). He was also called "Mecha Sonic" in the Japanese official strategy guide for Sonic Jam.

"Mecha Sonic" was confirmed as his an official English-language name in the backstory for Sonic the Hedgehog 4: Episode I, released on the US version of the official website, in the Story section.

Sonic the Comic
A Metallix robot based on Mecha Sonic appeared in Sonic the Comic's adaptation of Sonic & Knuckles. He stole the Master Emerald from the Hidden Palace Zone and was followed by Sonic and Knuckles to the Sky Sanctuary Zone. As in the game, he super-charged himself with the Master Emerald's energy, becoming invincible. However, he was defeated by Super Sonic when Sonic tried the same trick.

Trivia

 * Mecha Sonic is the first villain to manage to achieve a Super Form, the first inorganic character to ever use a Super Form (the others being Metal Sonic at the end of Knuckles' Chaotix, Gemerl at the end of Sonic Advance 3, and lastly, SCR-HD at the end of Sonic Riders: Zero Gravity), and the very first overall to trigger a transformation by use of the Master Emerald (the next would be Pir'Oth Ix, over a decade later).
 * He is also the only character with a super form that does not last long, forcing him to retreat to the Master Emerald for another charge up. The second half of the battle displays him remaining in his super form and no longer needing the Master Emerald to maintain it, though he is seen periodically reverting back to his normal form and then quickly powering up afterwards, hinting that his super form is also the only super form that is not stable.
 * The first phase of Mecha Sonic's battle theme during Knuckles's playthrough is the same as the battle with Eggman on the Death Egg, and the second phase is the same as the Doomsday Zone.
 * Mecha Sonic's fate in Knuckles's story depends on whether or not the player has collected all of the Chaos Emeralds (or Super Emeralds if playing Sonic the Hedgehog 3 & Knuckles). If the Emeralds aren't collected, then Knuckles will lose the Master Emerald, and Mecha Sonic will reactivate with the Master Emerald in his possession again. If all Emeralds are collected, then Mecha Sonic will be last seen breaking apart and Knuckles will reclaim the Master Emerald.
 * Mecha Sonic is used for the Alvin Earthworm series Super Mario Bros Z which is based off of Dragon Ball Z. He's powerful in his Super form.