Mecha Sonic and Metal Sonic by MechaSonicSuperFan on DeviantArt

ArtStation - Mecha Sonic (Sonic 3 and Knuckles)

Fanart] Mecha Sonic on Behance

Mecha Sonic (Sonic the Hedgehog 2), Sonic Wiki Zone

Mecha Sonic Revamp [BETA]

Silver Sonic Vs Sonic & Metal Sonic And Mecha Sonic

Mecha Sonic MK II (TheIronJedi), The Headcanon Island Wiki

Mecha Sonic Sprite Sheet by TheKnucklesMainG4 on DeviantArt

In Sonic 2 (8-bit), Mecha Sonic was designed so that its height matched Sonic's. In Mania, it still has that very same height: 32 pixels. : r/SonicTheHedgehog

Knuckles vs Mecha Sonic MK 2 by GardePickle on DeviantArt

Knuckles vs Mecha Sonic by thewax70 on Newgrounds