Codename: Kids Next Door

Codename: Kids Next Door (or KND for short) is a cartoon that was on Cartoon Network.

The show
In the show, it is shown that the Sector Z was kidnapped and brainwashed into the delightful children.

Operation L.I.Z.Z.I.E (Season 1, Ep 7b)
Numbuh 1 has a secret girlfriend who he often neglects because of his Kids Next Door responsibilities, forcing her to use a boyfriend helmet to mind-control Numbuh 1. If the helmet stays on for too long, it will start to merge with Numbuh 1's head and stay on forever.

Operation C.A.M.P (Season 1, Ep 9b)
A lost baby skunk interferes with a mission to rescue brainwashed campers.

Operation D.A.T.E (Season 2, Ep 2b)
The KND and nearly every kid in town are invited to a dance at the DCFDTL's mansion. However, it was actually a trap, all the party guests (except Numbuh 1 and Lizzie) are "delightfulized" like the DCFDTL.

Operation: Z.E.R.O.
The villains of the Kids Next Door, led by Benedict Wigglestein Uno (Father), join forces to resurrect the ultimate evil, Grandfather, a tyrant who once ruled the world many years ago when most of the villains were children themselves. However, Father disgraced him that he cannot even try to destroy the KND and the villains were quickly betrayed when they are turned into Senior Citizombies, creatures that are immortal and can transform any human being or any animal into one of them and slaves who are forced to make tapioca to refuel Grandfather so he can find and destroy the Book of KND. Once the villains were zombified (but not the teenagers and babies), Grandfather unleashes his wrath on the world, transforming almost humanity into old beings, turning the KND tree houses into tapioca factories, and the Kids Next Door including the backgrounder operatives in the city and Gallagher Elementary School rallies in defense, but were quickly overrun and zombified. Numbuh 1 is the only surviving KND operative to locate the KND's only hope for salvation, the legendary hero Numbuh 0 who turned out to be Montgomery Uno, Numbuh 1's father. In the process, Numbuh 1 discovers shocking revelations about the KND, his arch-enemies Father and the Delightful Children from Down the Lane, and even his own family history. Realizing that he is the only one standing, he makes a daring task to find Numbuh 0 and to save the world.