Dr. Eggman's Giant Robot

Doctor Eggman’s giant robot is a massive battle automaton unleashed on the newly formed alliance during the Attack on Mobius. Its appearance somewhat resembles the Doctor, and was originally powered by the Master Emerald when encountered by Sonic aboard the Death Egg (“Sonic and Knuckles” / “Sonic 3 & Knuckles”), but now seems to run under its own power. The enormous mech uses countless forms of weaponry to attack the group, including ocular laser blasts, appendage flamethrowers, heat beams, and various types of cannons firing from the chest, nose, etc.; it is also able to withstand numerous physical attacks, and can adjust its sight according to what direction an attack comes from. In addition, the robot can walk and create tremors with each step, as well as fly through the air to rush opponents.

The robot uses all of these abilities against the group as it attacks the land, and the group quickly finds that their punches and kicks, however concentrated or strong, do little to put the robot out of commission; they decide, in the long run, to divert the robot’s attention with these attacks as Knuckles, Tad, Mario, Luigi, and Yoshi subtly demolish the robot at close range. As Tad, Luigi, and Yoshi destroy some of the weapon mechanisms firing at everyone else and Knuckles oversees the plan being put into action from atop the robot’s head, Mario travels through its interior and obliterates its core circuits. After a lengthy battle, the robot finally explodes, its appendages flying in all directions.

Five years later, the robot's appendages suddenly begin rising out of the depths of the ocean, noticed by Sonic & company, and promptly reassemble, causing the robot itself to become fully-functional once more. Acting on its previous orders still, the robot immediately attacks Sonic and his allies, making prominent use of its past attack methods (ocular beams, chest cannons, propelling itself forward to rush targets, appendage flamethrowers). The robot even begins showcasing previously hidden features, such as an energy shield, the ability to launch its own hands into the air to grab targets—which Tails falls victim to—and bursts of electricity for paralysis, as performed on Cheese. Additionally, the robot uses its flamethrowers to set fire to the land, in order to trap Amy and Cream, preventing further attacks from them, and the robot is also able to detect Knuckles' attempts to free Tails from the grip of the robot's detached hand, which drags them both underwater.

Before the robot can stop Knuckles, however, Sonic and Gaz use Tak's ship to begin putting up a true fight against the robot, by penetrating its energy shield, dodging the ocular laser barrage and cannon fire, withstanding a blast of electricity paralysis, and successfully dismantling a portion of its overall weaponry. The robot's attention is later diverted by everyone else using their various attack strategies to put several of its functions out of commission, from the ground and in midair—while Sonic uses his blinding speed to rocket through the robot's body countless times, creating numerous gaping holes, which causes the robot to begin malfunctioning. In a matter of seconds, the robot is completely destroyed as Sonic rams into its head in one final attack, creating a massive detonation that obliterates any chances of further repair. At last, Doctor Eggman's giant robot is truly defeated.