Hyper Eggrobo is a giant robot with no legs. It is mostly gray with red circles. It also fires spheres. It has black hands, blue eyes and circles, and six little claws under it. If the player looks closely, G-merl's head is located on Hyper Eggrobo's head.
During the battle, Dr. Eggman will use the Hyper Eggrobo's two massive hands to attempt to squash the player. As he does so, he also takes out two of the four platforms the player has to stand on (although they will reappear later). At this point, the player can stand on the back of the rising hands to attack Eggman. Afterwards, Eggman will bring the hands to the side and begin creating red spheres from the blue sphere just above the emerald. This spheres can hurt the player and will push them back into the hands. However, they can also be stood on, allowing the player to again attack Eggman. The hands will play "Pong" in a sense, keeping the spheres bouncing back and forth. Eggman will also use the hands to punch and smash the player, signified by the hands either balling up and spinning in the background, or by going to both sides of the screen and moving up and done in an attempt to home in. G-merl is just above Eggman.
After eight hits (six in Easy mode), Eggman will escape with a damaged G-merl and the game will end with one of two possible endings, depending on the circumstances.
This is the only second-to-last boss in the Sonic Advance series not to have the name "Super Eggrobo," although it is likely an evolution of it.
It is also breaks the pattern of the past two versions being fought in stages named X-Zone and XX.
This boss can be easily beaten by playing as Cream, with Knuckles as a partner. This makes Cheese fly in circles around Cream damaging anything he touches, giving the player enough range to attack the Hyper Eggrobo by merely jumping from a platform at the right time.