Robo-Plankton is a robot clone of Plankton. Acted as a main antagonist in Battle for Bikini Bottom and SpongeBob's Truth or Square as a final boss. Robo-Plankton is the main hazard inside SpongeBot, attacking SpongeBob in different places. He can be driven off through use of a bubble attack.
Robo-Plankton's only attack is a sonic energy blast. In Truth or Square, it's attacks are increased. It has an ability to shoot pellets from it's machine gun hand, spitting robots out from it's mouth and trying to smack SpongeBob with it's fist (which allow SpongeBob to smack it, causing the giant robot's mouth to open and allow SpongeBob to went inside.).
Truth or Square
Another varient of Robo-Plankton is the final boss in Truth or Square. This version of the mech is built into the Chum Bucket, and thus, is Gigantic, unlike the Battle for Bikini Bottom version.The robot is not fought directly, like the other robots, and is instead fought from inside. Plankton originally uses this robot to attack Krusty Krab after SpongeBob says that he put the formula in the safe. However, when the robot's antennas are raised, it accidently being set to attack Bikini Bottom, not Krusty Krab. The robot is destroyed after SpongeBob went inside it's head and destroy it's core.
- The Truth or Square's version of the robot has a crossed-out picture of SpongeBob and Patrick on it's machine gun hand.
- During some parts of the battle against the Robo-Plankton (Truth or Square version), there are numerous pictures on the billboards on the buildings. One of them shows a picture of Mr. Krabs from Krusty Krab Training Video.