From Sonic Retro
This is the final boss encountered on both Sonic & Knuckles and Sonic 3 & Knuckles before the final battle. It's form resembles a minature Death Egg in which is protected by a rotating shield, it's base which opens up, releases small cars which host three sets of spikes which then travel around the floor of the Death Egg.
This boss is invunerable to any type of attack the player may try to inflict on it because of the shield is protecting it. The only way to inflict damage is to use it's own attacks against itself and that means using gravity as an advantage. The two transporters at the sides of the screen can allow you to walk on the ceilings or revert you to walking on the floor. When the boss releases the spike cars it's best to get ready to go into a transporter quickly. When the boss is just about to hover over the spike car, go into the transporter to turn everything upside down along with the car which will hit the boss if it's timed right. If that fails, then the car will be stuck because of the spikes in the ground. Spin Dashing into the car will flip it possibly hitting the boss if he is hovering near it. A word of caution, when the cars are left upside down, left to travel on the ground or hit the boss the wrong side, they will explode causing the three spikes to shoot out.