User blog comment:KillRoy231/My review of the Deadly Six/@comment-477304-20131021001503/@comment-26973802-20131021180735

But Metal Sonic was encountered in the white space and led Sonic to Stardust Speedway to fight for the Chaos Emeralds. It's not like the battle with Chaos. Sonic and all his allies, including Shadow and Silver, were there and remembered the whole thing after the timeline was restored, and so was Eggman.

Also, in Sonic CD, Sonic didn't kick Metal Sonic and blow him up, he got him to crash into a wall and fall over the edge. His body was still completely intact, and Eggman revives him. Good point about building another one, though. At the very least Metal Sonic is the third robot version of Sonic, with Silver Sonic and Mecha Sonic being one-shot minions. And Eggman Nega's Metal Sonic is Metal Sonic 3.0, who's Metal Sonic 2.0?