Drill Mobile

For the Marble Garden Zone Boss, Robotnik wants a battle in the sky this time, it seems. The first thing he does is smash the ground. While he's doing this, jump and hit him as many times as possible - 4 if you have no shield and no Super/Hyper Sonic or 7 if you do. After this, Tails will airlift you (or himself, if you're playing as him) so that you can jump and hit him.

When playing as Knuckles, the boss is completely different. Eggrobo will send some spiked wire through the ground and ceiling, which you must avoid. Then he will appear and collect the wire back in again. While he does this, hit him 2 or 3 times each time.