Not only does the rivalry escalate between Abby and the popular Paige, but a new villain named Insectiva uses pheromones to control giant termites that invade the city.
A bitter sewer worker named Slim merges with a slime mold and turns into a monster who attempts to smother the surface dwellers in slime.
A villain has been replacing ordinary ketchup with a substance that makes everyone fart, and collecting the resulting epidemic of gas to fuel his giant robot dinosaur.
Sloppy Joe, the world's grimiest villain attempts to capture all of the world's smelliest odors, in hopes to unleash a giant stink bomb upon the city.
A former beauty queen invents a weapon that allows her to emulate the Scab Fairy (like the Tooth Fairy) and steal people's scabs so that she can inflict them on others.
Criminals are using an infrasound ray gun that disrupts people's bowels so that they have to go to the toilet.
Insectiva creates a strain of head lice with mental powers that cause the kids at Ringworm High to obey her commands.
Fishy garbage is being stolen from all over the city, and the culprits turn out to be giant mutant hagfish.
An athlete's popular new brand of running shoes creates an epidemic of foot fungus.
A giant Owl terrorizes the people of town and especially its pigeons.
Sloppy Joe sabotages the city's water supply, causing everyone to start vomiting.
When Ty and Lab Rat design and build an experimental new vehicle that can move like an insect, super-villain Insectiva takes this as a challenge and goads Ty into a race.
A new boy in school causes organic materials to rot merely by touching them. Can Ty and Abby cure him?
While Ty engages in the annual Battle Robot tournament, Abby is reduced to cellular proportions by Lab Rat's shrinking ray so that she can battle Lance Boil through the hostile territory of Ty's bloodstream.
Super-villains Instectiva, Lance Boil and Sloppy Joe try to take over the city by infecting the Grossology team with a combination of internal parasites, halitosis and acne.
Deactivating a dangerous device created by Lance Boil causes Abby to be exposed to a ray that makes her age at an incredibly accelerated rate. The Grossology team has to find Boil and figure out how to reverse the process before it's too late.
Engaged in a science project competition with another student, Ty uses an unstable mutagen that produces super-evolving fruit flies that can't be stopped.
Stuck at school with Paige after missing the bus for a camping trip, Ty and Abby discover that a mad proctologist is using the nearly empty school to grow a giant intestine. But to what purpose?
When people start showing up with bite marks on their necks, Ty and Abby can't help but wonder if maybe vampires aren't a myth after all. But when they dig a little deeper, they discover that it's another kind of blood sucker that's causing trouble - leeches! Worse, these hungry invertebrates are led by 869, a giant mutated talking leech that's had enough of his kind being trapped in hospitals under harsh florescent lights. He only has one goal: freedom for leechkind!
Fartor returns with a scheme to turn the entire planet into a gassy giant! But for a plan this big he needs a new assistant - Ty.
Fartor and his new apprentice, Far-Ty join forces to drill into the planet core and turn the earth into one big gas planet. Will everyone on Earth be forced to breathe noxious gas and join Fartor’s army of the fart-breathers or will Abby with Labrat's help be able to save her Brother and the planet from a lifetime of stink!
Kid Rot returns and his powers are out of control.. The forest is rotting and Kid Rot is behind the destruction! Will Abby and Ty stop his rotting tide of evil before he destroys the planet?
A new super-villain, Darko Crevasse, uses an army of nighttime creatures to plunge the city into darkness.
Filthy villain Sloppy Joe returns with his new creation, a booger monster made entirely of snot, which is sucking up everyone's mucus.
When Abby is kidnapped and imprisoned in a greenhouse full of man-eating plants, her only hope of rescue lies with her enemy Insectiva.
Abby and Ty are invited to be contestants on a TV game show similar to Fear Factor, where their ability to withstand grossness is a big asset. The only problem is that it's actually a trap arranged by their arch enemy Lance Boil.