He looks like original PlanKrab, but with only one red antenna on his eye, red body and legs, no nose, and with green claws and eyelids. He also has Plankton's red eye pupil. He has Plankton's voice.
Role in episode
When PlanKrab sees Mr. Krabs and Plankton arguing in the bathroom, he splits into Red and Green PlanKrab and they start arguing with each other. Mr. Krabs and Plankton then tell the two PlanKrabs to shake hands with each other. The handshake causes them both to melt as well as getting rid of PlanKrab for real.
He seems to inherit more from Plankton than Mr. Krabs.