"Who's Who" is the 8th episode of Season 4. Dr. Gallio's latest invention gets tested, but it ends up switching the brains of Allstar and a snorkeater attemping to eat the entire town.
Three snorkeaters - Claude and a couple named Spike and Agnes - have plans on eating everyone in Snorkland. And at this point, they end up invading the town. Meanwhile, Dr. Gallio is working on his latest invention, the Mind Mixer. He tests it on a catfish and dogfish, and it works. But as they try to get the test subjects and switch them back into their rightful bodies, Allstar sees the snorkeaters coming, so he hides inside the Mind Mixer. Spike also searches for him in there, but their minds end up getting switched big time. Allstar is now in Spike's body and vice versa.Corky ends up grabbing "Allstar" while Agnes and Claude grab "Spike." Allstar, in Spike's body, tries distracting the snorkeaters by having them regroup and go elsewhere while Spike, in Allstar's body, tries eating Gallio when he realizes he's now a snork.
Corky goes off to find Ace, a snorkeater-eater, but he has a toothache, so he recommends his cousin instead. While Allstar tries distracting Agnes and Claude, they get upset with with him. The cousin of Ace shows up and tries eating Allstar, not realizing that Allstar is a snork trapped in a snorkeater's body. Agnes and Claude also capture Spike, not knowing he was really a snorkeater trapped in a snork's body, and they fight over him. Spike and Allstar soon meet up with each other, where they first fight over their bodies before coming to Dr. Gallio's. Gallio lets them use the Mind Mixter to switch themselves back to normal, which works. Once Spike is back in his body and Allstar his, Spike tries eating Allstar and Gallio. But Ace's cousin shows up and attempts to eat Spike along with Agnes and Claude. Allstar, being glad to be back in his own body, says he never wants to go through with that again, but Gallio only laughs about it.