Thread:Ultrasonic9000/@comment-1398428-20190725212854

Wasn't that part of Knuckles' route in Sonic the Hedgehog 3 while it was plugged with & Knuckles? Mecha Sonic appears as Knuckles' final boss on end of & Knuckles series, has seen used Master Emerald as its power-up to become Mecha Sonic's Super State.

Just thought this should be mentioned. 