The boss of Gene Gadget Zone pits Sonic against Robotnik on the conveyor belt of one of the Doctor's weapons machines. The ground scrolls under Sonic as pointy mines are trundled out of the innards of the giant manufacturing machine, requiring the player to dodge back and forth to avoid the mines. You can also jump over the mines if you wish. There's another trap awaiting at the foot of the conveyor, a sharp array of fixed spikes if the player fails to keep moving on the belt.
And above all this, the Eggman himself is floating around in his Egg-O-Matic, periodicly swooping down to ground level in order to strafe the area with missiles. Land a hit on Eggman once he's within low enough, but make sure you don't rebound onto a mine after doing so.