Egg King is a giant robot piloted by Eggman or Eggman Nega. The head has an Egg Mobile on it with a mouth guard. It also has spiky shoulders and big pillar-like hands with no fingers. Being a flying mech, it has no legs. It also has a triangular-shaped lower part with three fin-like blades around it. The character you are playing as determines the robot's color scheme:
Sonic: The upper torso, head, arms, and waist are white, the bottom torso, lines on the arms, spikes on the shoulders, hands, circle on the bottom torso, and spikes on the lower body is blue, and shoulders, arms, and lines on various parts are black.
Blaze: The upper torso, head, arms, and waist are white, the bottom torso, lines on the arms, hands, circle on the bottom torso is pink, the spikes on the shoulders are blue, and the shoulders, arms and lines on various parts are black.
The player must dodge hits and shockwaves or take damage. The arms must be knocked back to cause Eggman/Eggman Nega to go to one side of the ring and start "punching" the arena, sending out various shockwaves. When the arm gets stuck, the player must continue up the arm and attack the cockpit where Eggman/Eggman Nega pilot the bot. However, the pilot of the robot will try to shake their opponent off before the player reaches the cockpit, so they must hold on to avoid being knocked off (by holding down on the d-pad). After long, the robot slams both of its two fists onto the arena. A hit like this causes an instant death; however, this can be slammed back like a normal hit, a long as the fists do not directly contact the player. As the battle transgresses, the Egg King will begin firing cube-like objects at the arena that send out an electrical shockwave, and once in a while, a continuous wave that takes patience and precise movements to avoid. The Egg King will also fire lasers from its mouth that the player must avoid. The player again waits for the robot to slam its fists into the arena, sometimes at such a fast rate that it is almost impossible to retaliate. When the player finally lands the next to last hit, Eggman/Eggman Nega within the Egg King gets furious and determined to destroy their enemy for good.
The Egg King will then attempt to destroy the platform by slamming into it three times. The player must jump on its head again after its third time to finally stop the Egg King, which Eggman/Eggman Nega were too angry to realize. If the player takes too long to hit the Egg King, it will finally crash through and shatter the platform, causing the player to lose a life.
- Egg King is one of the two robot bosses to not be based off of an animal, the first being Egg Libra.
- It is possible that this robot was inspiration to the Egg Dragoon from Sonic Unleashed as the battle took place on a falling platform that is broken as the battle goes on.
- Egg King is very similar to a tie between Big Arm from Sonic the Hedgehog 3 & Knuckles and Diablon from Shadow the Hedgehog as both bosses are large hover robots and both serves as both the final boss and later the penultimate bosses of that game if the Player achieve a special condition, there are also other similarities as well.
- Both Big Arm and Egg King are similar as they are fought on a single platform.
- Both Diablon and Egg King are also very similar as they have the ability to shoot an energy laser from their heads and can swip at the Player with their hands.
- Intrestinly, both Shadow the Hedgehog and Sonic Rush were made around the same time.
- This is one of two Eggman bosses that is named after a ruling figure (the other is the Egg Emperor from Sonic Heroes).
- Egg King is the third final boss of the series to be comprised of an upper torso and arms, the first being Big Arm from Sonic the Hedgehog 3 and the second being Diablon from Shadow the Hedgehog.
- This is the second boss fight in Blaze's story where Cream is absent of cheering on Blaze since Cream is kidnapped by Eggman prior to the boss fight.