Metal Sonic

From Sonic - NeoWiki

In Sonic canon, there have been many incarnations of a Metal Sonic. The most commonly known one first appeared in Sonic CD, however, the idea of a robotic Sonic clone first came about in Sonic 2 with Silver Sonic.

Metal Sonic (Sonic CD version)

The original Metal Sonic was created by Dr. Robotnik. Its job was to kidnap Amy Rose the Rascal, as to lure Sonic into a trap. Metal Sonic was believed to be deactivated in a race on Stardust Speedway. Its next major plot line was in Sonic Heroes, where it creates a robotic Dr. Eggman to lure Team Sonic into another trap. This version of Metal Sonic believes it is the true Sonic, or that it is better than the real Sonic (an superiority complex).

Metal Sonic has a cameo part in Sonic Adventure, in a flashback with Amy and Sonic, and also appears as a playable character in the 2 player mode of Sonic Adventure 2, as well as being the final boss character in the arcade game, Sonic the Fighters.

Silver Sonic

Silver Sonic appeared in both 8-bit and 16-bit incarnations of Sonic The Hedgehog 2. In the Megadrive version, Sonic faced off this shoddy badnik at the top of the Death Egg, before he faced off against the final boss (a towering robot version of Eggman). It's 8-bit counterpart is far more powerful, and has a far more advanced moveset; in the game, Sonic cannot spindash, yet this robot version can.

Mecha Sonic

Also referred to as Metal Sonic Mk II, this version of Metal Sonic only appeared in Sonic & Knuckles. It serves as a distraction to stop Sonic getting atop the Death Egg, and as the final boss at Sky Sanctuary for Knuckles. It is worth noting that the Metal Sonic Mk II uses the Master Emerald to become Super.