As part of his latest plan, Krang brings General Traag to Earth from Dimension X as a distraction for the Turtles, while Krang tries to turn a laser at the ice and free the Technodrome from its prison at the North Pole. Meanwhile, Donatello learns a new fighting move, Wu Wei, where one ninja turns his opponent's attack against him without action.
When Bebop and Rocksteady accidentally wreck one of the computer chips in Krang's robot body and try to replace it with a chip from a portable game system, it comes to life and goes on a rampage. While chasing after it, Shredder has a big fall which makes him suffer amnesia. Meanwhile, Michaelangelo won't stop playing a video game, much to the other Turtles' annoyance.
Irma gets super magnetic powers and starts to fight crime. She decides to stop Krang's plan. When her powers wear off, the Turtles foil Krang and rescue Irma. Set on Halloween.
Michaelangelo accidentally turns Leonardo, Raphael and Donatello into 5-year olds with Donatello's "Food Revivafier" (a machine that turns old and rotten food fresh again), while Splinter is out.
A mystery ninja steals a powerful sword that belonged to his old ninja master in order to test the Turtles' ninja spirits.
A friend of the Turtles, Kerma, is hunted down by a destroyer because of a glitch in its sensors. The destroyer was supposed to hunt down a space pirate named Nerma, but the glitch made it come out "Kerma".
A vain, galactic outlaw named Shreeka is after her power ring that Krang took from her. The problem is that April O'Neil now has the ring.
A machine is causing the Earth to move closer to the Sun. Vernon's incredibly smart nephew, Foster, helps the Turtles on their adventure.
Donatello's newest invention, the "Dream-o-Vision" helmet, causes Michaelangelo and Leonardo to be stuck in a nightmare world, while the lair is being terrorized by a Freddy Krueger-like person.
Jammerhead uses the Bodyjacker to take over Darius Dun's body to steal O'Neil Tech's secrets.
When an alien ray makes him a super-genius, Slash returns to Earth, bent on turning the entire population of New York City into mutant turtles like him, with the intention of turning the whole world into mutant turtles so he can become the 'One Supreme Turtle', leaving Donatello to fend him off in a battle of smarts.
Leonardo gets lost and Raphael, Donatello and Michaelangelo must find him while Splinter is training. Meanwhile, after hearing about Leonardo's disappearance, Shredder and Krang use the Holographic Cloaking Machine on Bebop to make him look like the missing turtle, and have him cause trouble to ruin the turtles' reputation.
The Turtles try to solve a missing snake mystery, but Leonardo is afraid of snakes. A scientist who had a snake venom lab accident and turned into a snake tries to turn the city into a swamp.
Michaelangelo buys a parrot and names him Ditto, although the bird really belongs to a criminal who is after a rare key around Dido's neck because the Gulubi Ruby, the gem the thief stole, is in a vault that only the key can open.
Donatello's "Personality Alterator" turns Raphael too nice to fight. A mad scientist uses it to turn every policeman to nice so his robots can steal money and jewels.
Sh'Okanabo unleashes a time storm on New York, putting the Turtles in the middle of chaos.
Jammerhead escapes from prison and confronts the Turtles during a visit from Starlee's alien family.
An intergalactic mercenary enlists the Turtles' help in smuggling a ship full of humanitarian aid past Triceraton gangsters.
When Cody uncovers a secret weapons-manufacturing program, he and his uncle have a showdown over who will ultimately control the O'Neilltech empire.
Darius Dunn controls Turtle X to exact revenge on his nephew and the Turtles.
Triple Threat crashes a cross-country road race and steals all the cars.
The Turtles must rescue the president before he loses his head to a sinister figure from their past.
Dark Leo tries to prove himself by destroying the Turtles from within.
The leader of Inawashi Gunjin asks the turtles for help with a malicious alien.
When the entire population of Moonbase Bishop goes missing and the Turtles stage an assault on the base, they find a bigger Sh'Okanabo with an army of drones.
Torbin Zixx persuades the turtles to help him recover an experimental matter transmitter.