Metal Sonic is the “robotic counterpart” of Sonic the Hedgehog. As well as resembling Sonic, he can also perform many of Sonic’s moves, including his homing attack.
The first appearance of Metal Sonic was in Sonic CD for the Sega CD console. In this game, he is under the control of Dr. Robotnik and is sent back in time to change the past so that Dr. Robotnik can rule the future. Later, he kidnaps Amy Rose, who had been following Sonic. He was defeated in the Stardust Speedway zone.
Metal Sonic’s second major appearance was in Knuckles’ Chaotix, where he attempts to absorb the Chaos Rings’ powers to wreak havoc in the Newtrogic High Zone but was defeated by the Chaotix before he could. This occasion also featured his first power up, as he transformed into a massive, red version of himself called Mega Metal Sonic.
Metal Sonic appeared as a playable character. He is the only newcomer that was around but not included in the original Sonic Drift.