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 Gravity Hall, that has both roof and the ground part. When the boss enters the room, it is standing vertically, with one leg on the floor and one leg on the ceiling. It then squats down with both legs on the floor and the battle begins. 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 causes a trail of fire when it lands. The player needs to leap to the opposite path or otherwise the player will face losing rings or possibly a life. The player has to control the playable character over the gravity in this battle by pressing up or down-buttons on the D-pad, that flips the gravity in the respective direction, so use this technique to avoid the flame trails from the bombs and hit the Eggmobile.
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 stage, the final stage of the game that is a boss rush. There, it has the same beginning movement like in original fight and after that, it mostly does the same attack patterns. However, it only takes four hits to be destroyed.
- Egg Frog has very similar composition comparing to Egg Spider from Sonic Advance.
- Eggman seem to upgrade this machine, as it later appears as Egg Foot in Sonic Advance 3.