Giga Metal Sonic

Giga Metal Sonic is a transformation of Metal Sonic, when getting the Phantom Ruby.

History
During the final phase of his battle with Sonic, Tails, and Knuckles, Metal Sonic received the Phantom Ruby from Infinite. The ruby's power allowed Metal Sonic to transform into Giga Metal Sonic, and he proceeded to fight the heroes with renewed power. However, by shattering the container on his chest that held the Phantom Ruby, the heroes managed to shatter the illusion that created Giga Metal's form, resulting in Metal Sonic's defeat.