The Egg Frog (エッグフロッグ,Eggu Furoggu?) is the seventh boss in Sonic Advance 2. It is the boss for Egg Utopia and is controlled by Dr. Eggman. The player has to hit to the cockpit eight (six in easy mode) times to destroy the Egg Frog completely.
The Egg Frog's appearance actually looks more like a spider than a frog. It is mostly gray, with yellow headlights, orange parts on its legs, and dark-gray feet. An Egg Mobile takes up most of its body.
This battle is centered on an endless hall where Rings will generally spawn in mid-air. Unique to this fight, the player has the ability to inverse gravity with Up (while on the ground) and Down (while on the ceiling) on which is essentially useful in this battle. Jumping on it The Egg Frog uses its legs to jump the ceiling to the floor and vice versa. When Egg Frog does this, it drops a missile below it, which explodes into a trail of fire when it lands. A Spin Jump alone will not be able to avoid this attack so the player will need to invert gravity as well.
Egg Frog is able to decrease its speed, causing it to move backwards. You can see this by looking the pose of its legs, as the Egg Frog will stiffen up. which the player can also avoid by switching the gravity. When Egg Frog returns back from off-screen at left side, it comes in a burst of speed which has to be avoided as well. After four hits, Egg Frog goes into pinch mode, where keeps doing its backwards moving and surprise attack even more. Once hitting the Egg Frog four more times, it will be destroyed.
Egg Frog later reappears in XX, the final Zone of the game which serves as a boss rush. There, it has the same beginning movements like in original fight and after that, it mostly does the same attack patterns. However, it only takes four hits to be destroyed.