Young Johnny is gung-ho and full of courage. Johnny's brainiac twin sisters, Susan and Mary, use Johnny as their guinea pig for their outrageous scientific experiments. If they can dream it up, Johnny will do it; as long as his genetically engineered super dog, Dukey, can come along.
Episode 1
Things have been mysteriously disappearing underground, making Johnny and Dukey believe that the people behind this are "mole people". When Johnny accidentally loses his dad's new camera, he must journey to the center of the earth to retrieve it before dinnertime, or he will be grounded.
Episode 2
Susan and Mary give Gil a piece of their special love "bubble gum", but by accident, it makes him transform. In order to save Gil and the others in pork belly, they have to give Johnny and Dukey some cool super powers.
Episode 3
Bling-Bling Boy has stolen a device that turns things into gold and Johnny must get it back before dinnertime.
Episode 4
Johnny tries to get his baseball back from an old man before the baseball game starts.
Episode 5
Susan and Mary are having a party and use a device on Johnny in order to make him look good so all the girls at the party will love him, but Johnny turns into a monster.
Episode 6
The Extreme Teen Team are on the loose and it's up to Johnny to bring them down.
Episode 7
Johnny uses an invention to breathe underwater, yet sharks and electric eels begin to walk on land and wreak havoc to the beach.
Episode 8
Bling-Bling Boy steals a backpack and Johnny must retrieve it so Susan and Mary can show it off at the school science fair.
Episode 9
Johnny goes back in time to ask Thomas Edison for a hockey invention and then to gather all of the vicious and ruthless "legends" he could find, in order to form a hockey team which will help the Ice Pigs win a game.
Episode 10
Johnny fills the house with some of Hugh's favorite things listed in his notebook. However, Johnny learns that the book was also full of Hugh's least favorite things (most of them scary.) To make matters worse, Lila's boss is coming over for dinner that night.
Episode 11
Johnny wears super smarty pants in order to win the love of a genius girl, Janet Nelson Jr. But later, the pants get a mind of their own.
Episode 12
Johnny sneaks into Lila's car along with Susan and Mary on Take Your Daughter to Work Day, thinking that it's unfair that girls don't have to go to school on this day, but boys do. When the kids get to Lila's workplace, they sneak into a lab and accidentally release a missile.
Episode 13
Johnny brings a toy, Nasteria, to life. But the toy decides to destroy Porkbelly. Now Johnny needs to stop the evil action figure with a toy force, led by Nasteria's arch enemy, Mega Roboticle.
Episode 14
Johnny steals a rocket his sisters made to travel to the moon so he can write his report. Unexpectedly, he battles some moon monsters and rescues Canadian astronauts.
Episode 15
Johnny uses a gadget to travel into a movie, The Quickest and the Monkiest. But what happens when the gadget gets stuck and the movie has a bad ending?
Episode 16
Johnny's sisters invent a time rewinder that can go back up to 5 minutes and they use it to get Johnny in trouble. Infuriated, he tries multiple times to steal this, but he fails; eventually, he gets a similar one from Bling-Bling Boy.
Episode 17
Johnny becomes Johnny X again in order to take down Bling-Bling's latest evil invention, Repto-Slicer.
Episode 18
Johnny and Dukey try Susan and Mary's ultimate scooter and are wanted in the future.
Episode 19
Susan and Mary put a device on Dukey, making him respond to their every command. Now Johnny must stop Susan and Mary, and get his best friend back.
Episode 20
Johnny uses a device to free everyone of zits.
Episode 21
Johnny uses his game controller to control people, but Hugh gets his hands on it and begins affecting Johnny in the process.
Episode 22
Johnny accidentally shrinks himself and Dukey into a sub-atomic universe while shrinking his toys. Unexpectedly, its nature turns against him.
Episode 23
A kid at Susan and Mary's school becomes a villain named Brain Freezer. Now Johnny must stop this villain and unfreeze everyone he froze.
Episode 24
Johnny uses a device in Susan and Mary's lab to make it snow outside.
Episode 25
Johnny uses a bionic arm to magnify his arm strength to beat Sissy at dodge ball. However, it breaks after being exposed to cereal.
Episode 26
Eugene brings a living monster truck to the Test house, and it began to be enraged after Eugene kicked it because it didn't win Susan's heart. Now the truck wants to destroy the entire monster truck species. It's up to Johnny to figure out how to stop it.
