History WesternAnimation / OperationZERO

* ParentalFavoritism: Ironically, Grandfather always favored his oldest son, the one who defied him and disappointed him by refusing to use his skills for evil (and instead overthrew his evil empire). Father is just as evil as he is but has still always been TheUnfavorite for being a constant failure. Even after being recommissioned by the latter, Grandfather ''still'' says he prefers the former despite destroying his powers.

** "This is going to be...delightful." ([[spoiler:Sector Z]] taking on the zombified Sector V)

* BittersweetEnding: [[spoiler: Grandfather is defeated and the world is saved... but the Moonbase had to be destroyed to get there, though a new, radically-changed one is built some time later. Monty's identity and actions as Numbuh Zero are revealed to the Kids Next Door, and he is hailed as a hero, but he has to decommission himself to ensure his maturity sticks and that he remains a good father, something that even Nigel had a rough time accepting. On top of that, Sector Z is ''still'' stuck as the Delightful Children with no possible permanent cure for their condition, with only Nigel so far being aware of that knowledge, and Father is still at large. For the most part, however, Nigel's bond with his Sector V teammates and Numbuh 362 is stronger than ever before and the organization is widely more united behind his sector.]]

* EvilerThanThou: Grandfather turns all the villains into his elderly undead slaves ''very'' quickly, which lets you know that things are ''really'' bad now that he's back in town.
* EvilIsNotAToy: Almost immediately after being recommissioned, Grandfather harshly dismisses his son with no true signs of thanks for reawakening him, pointing out that the only reason he needed to be brought back is because Father and the other villains weren't able to stop the KND themselves.

* ExactlyWhatIAimedAt: Sector V drops the ''entire'' KND moonbase [[spoiler:upon Grandfather]]. He survives, and gloats to Monty that it didn't crush him at all. Monty retorts that the plan was not to crush him to death, but to bring the Decommissioning Chamber (planted in the Moonbase).

-->'''Numbuh One:''' Wait a minute... This is [[spoiler:''my'']] house!

* BalkingSummonedSpirit: Father reawakens the ancient evil Grandfather in his latest plan to bring the Kids Next Door to his knees. He thanks his son for doing so... and then immediately casts him out knowing that he's only being summoned now because the villainous adults need a Godzilla Threshold. He then takes over his whole plan and nearly takes over the world.

* BigGood: [[spoiler: Monty Uno, Numbuh One's father, is revealed to be Numbuh Zero, the founder of the modern age of the KND Organization. After getting recommissioned, he comes up with a plan to help his son save the world from the clutches of his evil father, Grandfather]].

* ExactlyWhatIAimedAt: After Sector V drops the ''entire'' KND moonbase [[spoiler:upon Grandfather]]. He survives, and gloats to Monty that it didn't crush him at all. Monty retorts that the plan was not to crush him to death, but to bring the Decommissioning Chamber (planted in the Moonbase).

* BittersweetEnding: [[spoiler: Grandfather is defeated and the world is saved... but the Moonbase had to be destroyed to get there, though a new, radically-changed one is built some time later. Monty's identity and actions as Numbuh Zero are revealed to the Kids Next Door, and he is hailed as a hero, but he has to decommission himself to ensure his maturity sticks and that he remains a good father, something that even Nigel had a rough time accepting. On top of that, Sector Z is ''still'' stuck as the Delightful Children with no possible permanent cure for their condition, with only Nigel so far being aware of that knowledge, and Father is still at large. For the most part, however, Nigel's bond with his Sector V teammates and Numbuh 362 is stronger than ever before.]]

** As part of a last ditch effort to combat Grandfather, Numbuh Two attempts to modify their Age-O-Tonic Birthday Suits to resist Grandather's Seniorcitizombification but only manages to complete one before being transformed himself. After the Seniorcitizombified Sector V is defeated, Numbuh Two stumbles into the closet filled with the Birthday Suits, with the one he finished falling onto his head.

** Numbuh One boasts that he has a super cool new move that can take down four enemies at once. Unfortunately the first time he tries to use it, the villain had just succeeded with their goal and called a retreat before he could even attack one of the four guys around him. Then he thinks to use the move a second time later in the movie, but because it's against [[spoiler:his zombified team, he hesitates and ends up defending the whole fight until Sector Z comes to help]].

* ThroatLight: All the characters turned into Senior Citizombies have streams of light pouring out of their eyes and mouth during the transformation.

* TheVirus: Anyone Grandfather or a Senior Citizombie touches becomes a Citizombie themselves.

** Grandfather's slave armies takes over KND bases, zombifies their operatives and turns their treehouses into tapioca pudding factories.

* DirtyCoward: Father, ironically, [[spoiler:was this as a child. Instead of trying to save the world with his brother Monty a.k.a. Numbuh Zero, he sticks with Grandfather just to save his own hide. Though he's rid himself this trope as an adult, he STILL refuses to join his brother in fighting their father. Except this time it isn't out of fear but rather he's too dejected from Grandfather disowning him to even care anymore.]]

* BigBad: Grandfather.

* BigNo: In the DistantPrologue, Grandfather shouts this, as his powers are destroyed.

* EnemyMine: Numbuh One and Numbuh Zero works together with Father and the Delightful Children [[spoiler:a.k.a. Numbuh Zero's brother and Sector Z, respectively.]]

* ForgotAboutHisPowers: The KND are equipped with vehicles that allow them to fly into space including their Moon Base. When the Senior Citizombies come for them, the first KND Treehouse base choose to counterattack failing to realize just how vastly outnumbered they are and retreat.

* MacGuffin: The Book of KND and to a lesser extent, the Recommissioning Module.

** The zombified Toiletnator [[BuildingSwing swings around using toilet paper]], and lowers himself upside-down in a posture typical of Franchise/SpiderMan.

* OurZombiesAreDifferent: The Senior Citizombies. They're always old no matter how old they actually were before they're transformed, but they're still very capable fighters and are able to age-ify others. They also retain their basic memories and personalities (which partially explains the RomanceEnsues moment between Numbuh Three and Numbuh Four), although they are totally subservient to Grandfather.

* BambooTechnology: But of course.

* BothSidesHaveAPoint:
** Numbuh 362 (the current head of the KND) admits that Numbuh One was ultimately right to prioritize the KND Museum over the Moonbase and for believing in Numbuh Zero.
** Numbuh One admits that she was right about him putting himself before his teammates, without whom he wouldn't have been able to pull off ThePlan.

* BrainBleach:
** The museum visitors get grossed out when they learn the statues of the RoguesGallery are all made out of earwax.
** Everyone else is repulsed by a zombified Numbuhs 3 and 4 making out.
* BroughtDownToNormal: Grandfather needs his memories in order to use his powers, hence the reason why Father recommissions him. [[spoiler:As such, when Monty Uno transforms him back into a normal old man, everyone who had been transformed into a Citizombie turns back to normal.]]

* GodzillaThreshold: Numbuh Zero isn't too surprised at being recommissioned and is ready to go back into action, and knew that Numbuh One would have only done so if the situation was [[DarkestHour so dire]].

* HiddenBadass: [[spoiler: Monty Uno, who is Numbuh Zero]], despite how he seems like a clueless, gullible BumblingDad for the most part.

-->'''Father:''' This man... this hunchified, liver-spotted creature with hair growing out of his ears was once the ''supreme'' power in the world, until he was defeated by a misguided boy and his ''stupid'' book! A boy who wiped Grandfather's memories clean and evaporated his powers before my eyes! But now, I -- ''his son'' -- will restore his evil abilities and together we shall return the world's snotty brats to their rightful place!

* MyGodWhatHaveIDone: Numbuh One gets this when he realizes that by going to the convention center to try to stop the villains, he had given them the key to their victory.

-->'''Numbuh One:''' Wait a minute...This is [[spoiler:''my'']] house!

* AlmostKiss: Numbuh Three and Numbuh Four look like they're ''seriously'' close to doing so when Numbuh Five corners them...but they get interrupted by hamsters.

* AscendedFanboy: Numbuh One is [[TheKnightsWhoSaySquee positively giddy]] over working with Numbuh Zero.

'''Numbuh One:''' [[spoiler:Un-Un-'''''Uncle?!''''']]\\

'''Numbuh One:''' [[spoiler:But if you're my uncle, then that makes Grandfather my grandfather!]]\\

** Second, it turns out that [[spoiler:Father is actually Monty Uno's brother, the one who refused to fight [[BigBad Grandfather]] years ago. Making him ''Numbuh One's biological uncle, and [[ShapedLikeItself Grandfather his grandfather!]]'']]

** HowIsThatEvenPossible: Grandfather lampshades this by asking his son Monty how he can hold on for so long while the two are locked in combat as Monty's arms start to turn a grayish green. Monty explains the Book of KND in his back pocket is what is keeping him from being fully turned into a senior citi zombie.

HowIsThatEvenPossible: Grandfather lampshades this by asking his son Monty how he can hold on for so long while the two are locked in combat as Monty's arms start to turn a grayish green. Monty explains the Book of KND in his back pocket is what is keeping him from being fully turned into a senior citi zombie.

** Numbuh 362 (the current head of the KND) admits that Numbuh One was ultimately right to prioritize the KND Museum over the Moonbase and for believing Numbuh Zero.

* ButNowIMustGo: [[spoiler: Nigel's dad Monty re-erased his memories as part of the plan to destroy Grandfather. He also destroyed the Recommissioning Module beforehand to prevent his son from re-restoring them. He explains in a recorded holographic message on the module that he did so because "I am simply not a kid anymore. I'm an adult and now I must carry the greatest mission of my life...to be a good father to my son". In this case, he is not physically gone but simply took away his Numbuh Zero persona to identify this trope.]]

* CainAndAbel: [[spoiler: Numbuh Zero and Father.]]