You may be looking for Egg Dealer (Sonic Rivals 2).
The Egg Dealer is fought after the levels Black Comet (Hero mission), Lava Shelter (Hero or Dark mission), and Cosmic Fall (Dark mission). The potential guides for the battle are therefore Knuckles, E-123 Omega, and Vector.
It has four rigid legs which it stands on. It also has slot reels on the front of its body, which can be stopped individually by using the Homing Attack on the buttons below them. The cockpit can be attacked by the laser carried by the Egg Pawns, although this is inefficient. Shadow can also damage it by stopping the reels so that it bombs itself (Bomb Fever) or fires a volley of missiles at itself (Missile Fever). Shadow's Chaos Blast power is also effective. If Eggman gets nothing (example: missile, missile, pawn), three boxes will appear in the middle of the stage with an egg gun, lance, or bazooka.
After aiding the G.U.N. counterattack on the Black Comet and penetrating the comet's defenses, Shadow and Knuckles find Eggman at the Comet's heart trying to steal the Black Arms' Chaos Emerald. After destroying the Egg Dealer and taking the Emerald for himself, Shadow declares that he is master of his own life and will live a neutral existence. He then finishes off Eggman with a knifehand strike.
In the Dark version of the boss fight, despite obeying the doctor's orders and sealing the shelter with lava, Shadow decides to fight Eggman in his slot-machine based monstrosity for the Chaos Emeralds. After his defeat, Eggman asks why Shadow betrayed him and Shadow replies that being revealed as an android only fueled his semi-crazed patricide instead of serving Eggman. He vows to use the Emeralds to become even more powerful than the original Shadow, completely unaware that he is the original Shadow. He then finishes off Eggman with a knifehand strike.
In the Hero version of the boss fight, Shadow helps Omega obtain the Chaos Emerald in Dr. Eggman's lair, and confronts the fat man himself in his oddest machine yet. Eggman finds himself in the midst of robotic retribution after his last humiliating defeat, as Shadow, believing himself to be an android, decides to use the Chaos Emeralds to take over the Eggman Empire, and establish a whole rule of Androids. Just after Eggman reacts to his intentions in shock, Shadow and Omega kill their creator.
Eggman shows up on the ARK after Shadow grabs the last Chaos Emerald and exclaims that although his grandfather created Shadow, he should give him the Chaos Emeralds. After Shadow refuses, a confrontation between the two. With all seven Emeralds in his possession, Shadow vows to use them to protect the ARK, and spares Eggman on the account that he never returns.
Notably, this is the only ending where Shadow fights Eggman in the Egg Dealer, and lets him live afterwards.
The attacks it can use are:
- Missile Fever - Eggman starts the battle with this attack. The machine launches a volley of six missiles that target Shadow if launched by Eggman and versa if launched by Shadow. If the player continues to lose lives, Eggman will start the battle by accidentally launching it on himself.
- Bomb Fever - The machine drops explosive red spheres. If Eggman executes the attack, the Egg Dealer continues moving around the arena dropping bombs. If Shadow executes the attack, the Egg Dealer trips and blows itself up.
- Pawn Fever (Eggman only) - Summons a couple of spear-wielding Egg Pawns.
- Ring Fever (Shadow only) - Causes a massive amount of Rings to appear in the center of the arena.
- Shadow Fever - When launched by Shadow it maximizes Shadow's Dark Gauge, allowing Shadow to transform into Dark Shadow use Chaos Blast. When executed by Eggman, it summons three Shadow Androids.
- This is one of the few (if not the only) Eggman's robots that actually helps the player defeat it under correct circumstances.
- There is another boss named after this robot.
- Whenever Shadow is battling the Egg Dealer, he is partnered with a Power-type character.
- This is the only one of the final bosses of Shadow the Hedgehog to take both the hero and dark endings of a stage.