Electro-Koopa

Electro-Koopas are Koopas found in Super Mario Sunshine. There are three kinds of Electro-Koopas, all of which walk on all fours and have electrical shells. They are mostly found in Pinna Park, though the blue-shelled Electro-Koopas also appear in the King Boo fight.

Blue-shelled
Blue-shelled Electro-Koopas are the smallest and most common type. To attack, they will throw their shells at Mario; if he doesn't dodge them, he'll get Electrified. The shell will fly back onto the Electro-Koopa like a boomerang. To defeat them, Mario can either stomp them once they've thrown their shells, or spray them with water to distract them and cause them to get electrified by their own returning shell. If an Electro-Koopa throws its shell over a cliff, thus preventing it from returning, the shell will disappear after a few moments, and the Electro-Koopa will spontaneously grow a new one. Similarly, the shell will be destroyed if it lands in water, though it still takes some time before the Electro-Koopa replaces it.

Red-shelled
There are also red versions of the Electro-Koopa. They appear in Pinna Park and Pianta Village where they climb on metal screens. To defeat them, Mario should kick, punch, or Ground Pound them from the other side of the screen. When this happens, they fly off into oblivion. They will shock Mario if he comes in contact with them.

Green-shelled
There is also a green breed that resembles a giant Electro-Koopa, similar in appearance to the red-shelled variety. It slept atop the ferris wheel in Pinna Park where electrical discharge from its shell made the ride spin extremely fast. Mario had to defeat the Electro-Koopa by flipping the grate beneath its belly; it'll then fall in the water, causing a Shine Sprite to appear and allowing the ferris wheel to returns to normal speed. It might be a leader among the Electro-Koopas.

Trivia

 * A shell-less Electro-Koopa appears in the board game Nintendo Monopoly.