Volcano Valley Zone boss
From Sonic Retro
The Volcano Valley Zone Boss involves Robotnik's Eggmobile being in the control center of some pipes. These pipes spout mini-flames and the center console spouts one large flame that follows you. The goal is to get to the middle on the pipes and hit him. 7 hits will destroy Robotnik. There are rings on each corner, so use those, and don't touch the lava!