Dohyo Master, known as Mecha Buta (メカブタ) in Japan, is the third boss of the 8-bit versions of Sonic the Hedgehog 2, fought at the end of Green Hills Zone. It is an unusual sumo wrestler-like pig robot.
The boss fight against Dohyo Master takes place in a bowl in the terrain, which varies in shape depending on version. In the Master System version, the bowl's slopes are gentle, whereas in the Game Gear version the bowl is conspicuously steeper as a result of the smaller screen size, making it difficult for the player to stay in control.
This bizarre boss attacks in a similar way to Sonic himself - namely, by curling into a ball and trying to ram his opponent in imitation of the hedgehog's Spin Attack. The mechanical pig's Spin Attack can go in several direction; the pig can jump across the arena, roll horizontally from one end of the screen to the other, simply roll across the floor, or even combine two of these trajectories. After it is finished rolling, the pig will bounce on the edge of the screen, uncurl, and stomp its feet, giving Sonic a chance to get an attack in. Repeating this six time vanquishes the porcine foe, granting Sonic free passage to Gimmick Mt. Zone.
The conspicuously steeper arena in the Game Gear version