G-merl and Hyper Eggrobo (ハイパーエッグロボ Haipaaeggurobo) are the eighth bosses of Sonic Advance 3, and are the regular final bosses of the game unless the player collects all 7 Chaos Emeralds and the leader is Sonic.
G-merl is the first boss the player will encounter, and will employ all the tactics of his previous fight in Cyber Track. He'll attack by dashing side-to-side, before warping into the air and dashing across the screen, unleashing a volley of missiles. He'll also move to the top-center of the screen and begin spinning, unleashing a spiral of missles that will hit the ground and the player if they are not careful. G-merl is fast and will take 4 hits as per usual (2 on Easy) to defeat before you can move on.
Eggman will use the Hyper Eggrobo's two massive hands to attempt to squash you. As he does so, he also takes out two of the four platforms the player has to stand on (they'll reappear). 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 and will also 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. When you finish the fight, either of below could happen, depending on if you have all 7 Chaos Emeralds or not, and if the leader is Sonic or not:
- 6 or less Emeralds/Have all 7 Emeralds, but leader not Sonic: Both Eggman and G-merl run away, but you hit Eggman's Eggmobile, G-merl jumps off the edge, and the game ends with the Master Emerald restoring the shattered world.
- 7 Emeralds with leader Sonic: Both Eggman and G-merl run away, but G-merl jumps off Eggman's Eggmobile, steals Sonic's Chaos Emeralds, and becomes his super form. He runs off, but Sonic uses the power of the Chaos Emeralds, and becomes Super Sonic. Eggman & Sonic team up, and the true final boss starts.