I would be thrilled to report that I loved “Plankton: The Movie,” a “SpongeBob SquarePants” spinoff film. I'd love to say that it is the cinematic hit of the spring. Alas, I cannot.

Sheldon J. Plankton, the owner of the Chum Bucket, has been a staple of SpongeBob SquarePants since the first season. His ...