The robot suits are extremely durable; their only weak point is their one huge eye, and even then it takes many, many hits to take one down. The robot suits are equipped with four jets on their undersides which allow them to fly, as well as two arms whose hands can turn into weapons. The nature of these weapons varies between different units. Additionally, the suits have extra abilities that they can use after they certain amounts of health.
Plankton is the first boss of the game, encountered at the end of the first level of Dutchman's Triangle. His robot suit is colored lime green and is modeled after Plankton himself. It has guns for hands, and is able to shoot laser bullets at the player. Plankton will usually stay in one spot and continuously fire bullets at the player, but as he loses health he will periodically move from side to side while firing bullets straight ahead, forcing the player to jump to avoid the bullets.
Whenever Plankton's suit loses 1/4 health, he will fly off-screen and spawn several enemy robots that must be defeated. Once they're destroyed, Plankton will fall onto the ground to try and crush the player before floating back to the background to resume his normal attack patterns.
Plankton's suit is also the strongest one of the bunch, as it survived the first battle with SpongeBob and friends, allowing Plankton to escape with his suit still intact, albeit moderately damaged.
Rainchild is the second boss, encountered at the end of Dutchman's Triangle. His robot suit is colored metallic blue and is also made in his likeness. His suit also has gun hands, but they shoot solid laser beams instead of bullets. Most of the time, Rainchild will sweep laser beams across the arena, requiring the player to constantly jump to avoid taking damage. Later on, he'll also fire beams straight ahead and move from side to side, much like Plankton.
Whenever Rainchild loses 1/4 of his health, he'll shoot several blobs of tar at the player to try to get them stuck, and then sweep one gigantic laser beam across the arena that can only be dodged by double jumping over it. Rainchild is immune to damage during this attack.
Clem is the third boss, encountered at the end of Rock Bottom. His suit is also made to look like him, but for some reason it is colored purple instead of light green like Clem himself. Clem's suit features the same gun hands as its predecessors, but this one launches bombs instead of laser-based projectiles. During his battle, Clem will constantly lob bombs at the player. He does not gain any new abilities as the battle progresses, but he will shoot faster the more damage he takes.
Whenever Clem loses 1/4 of his health, he will lower himself to be level with the arena platform and shoot many time bombs onto the ground. The player will have to either run to a safe spot or jump to avoid the explosions. Clem is immune to damage during this attack.
Plankton is encountered again at the end of Bikini Bottom, serving as the game's final boss. In this battle his health is divided into ninths instead of quarters, and he uses a desperation attack every time he loses 1/9 of his health. Initially, Plankton will follow his own attack patterns. However, once he loses 3/9 of his health, he'll switch to using Rainchild's attacks instead. And after losing 6/9 of his health, he uses Clem's attacks. Defeating Plankton in this battle will end his evil scheme for good... or will it?
No, it turns out Plankton's robot suit has one last trick up its metallic sleeve... upon its defeat, the robot suit will lose its arms, only to gain two disembodied fists in their place! With these fists, Plankton will try to crush the player with various attacks which include slapping the ground with one hand several times, pounding the ground with both fists, and slamming his fists together. Plankton doesn't use any desperation attacks during this phase, but his attacks get faster over time as he takes more damage.