Adult Fear: As goofy as it was, there's the pretty freaky premise that at some point, your co-worker could turn on you, steal everything you've ever done, perform an extremely painful procedure on you, and turn the entire town against you, completely ruining your life. And when he's done with that, he'll do it to your kids.
Artistic License - Biology: There's a reason why they are called whale sharks. Whale Sharks are shrimp-eating, filter-feeding, peaceful creatures that do not have giant sharp teeth and are not dangerous to anything larger than a tiny fish.
Body Horror: The consequences of gene-slamming, especially on Dr. Bolton. He's never seen on-screen after his transformation, but from the looks of his shadow and the gurgling noises made whenever he appeared, Dr. Bolton became something truly grotesque.
Cross Over: The Extreme Dinosaurs make appearances in the last season, though with a different name (Dino-Vengers) and backstory.
Destructive Saviours: It's not uncommon for the Street Sharks to cause some severe property damage whenever they save the day, such as destroying the eponymous streets by swimming through the solid concrete. On the other hand, when they level buildings and such, it's usually in an effort to prevent worse disasters, like sinking a parking garage to avoid flooding the city with nuclear fallout.
Disappeared Dad: After showing up once in the pilot and being turned into a monster offscreen, the Sharks' dad is never seen again. His absence is the main concern of the heroes and finding him is usually their first priority.
He sometimes appears in shadows, or as a 'just missed' character. He is still a major plot element, actually.
Dying Like Animals: The entirety of Fission City had apparently been gene-slammed with lemmings years ago. They eagerly believed every word out of Dr. Paradigm's mouth and gladly complied with even his most transparent evil schemes. It took the Sharks forcing him to transform into his "Pirahnoid" form on national television to dent his credibility.
Extreme Omnivore: The Street Sharks can and do eat just about everything from hamburgers to steel girders and concrete without indigestion. Just don't offer them pizza.
Hero with Bad Publicity: Paradigm could blame the Sharks for anything he did and the citizens of Fission City would accept without question. It's taken to such extremes that one of their friends has to explicitly tell the police that, if they really were guilty of one of the crimes they were accused of, they'd have to be in two places at once.
Missing Mom: Their mom is virtually nonexistent and is only mentioned once in the pilot, when it is revealed that she once gave their dad a watch and it was implied that she was dead.
Obviously Evil: Dr. Paradigm. True, giant shark-men aren't exactly going to inspire confidence, but does that really mean that you should trust a man who has an eyepatch and an indeterminately European accent who goes around town in a giant, heavily armed diving suit? Of course he'd still set off villain alarms in civilian garb. Paradigm tries to subvert it by claiming that the suit's main purpose is a life-support system, after a run-in with the Street Sharks.
Painful Transformation: Every transformation includes a lot of pain as the transforming characters nearly always scream in pain.
Pinocchio Syndrome: One of the main goals of the protagonists is to get turned back to humans, though this tends to take backseat, since they're better-equipped to fight a villain and his mutant underlings with mutant powers themselves than without.
"The Reason You Suck" Speech: In one episode, the mutated Doctor Bolton singlehandedly defeats Dr. Paradigm's forces to rescue a mutant. He tears off Paradigm's suit, revealing his grotesque Piranoid form, and mocks the cowering villain, claiming that he has become something far less than human.
Take That: Quite blatant "Take That" to the Jurassic Park toys on the back of the "Big Hand Puppet" toys' box. There was a small picture of one of said puppets smacking one of the T-Rex toys from said rival toy line.
Also a blatant shot at the TMNT when during an early episode the four were disgusted at the idea of eating pizza.
They Would Cut You Up: Justified, since the pilot has a part where all four are recaptured and Slammu is very narrowly forced to undergo "explorative surgery". He's saved and the others are tempted to try the same surgery on the doctor.
Trademark Favorite Food: Hot dogs and hamburgers, though they seemed to eat anything. In a reference to the Ninja Turtles though, they all hated pizza.
A case of Fridge Brilliance as Sharks are generally predatory animals and would prefer eating meat.