Made of Iron: Everyone, the most notable being the time when Shego got kicked from the roof of a building that is several stories high, into an electrical signal tower, which not only electrocutes her but also collapsed right on top of her. And she comes out of the incident with slightly torn clothes and frazzled hair...
Masculine Girl, Feminine Boy: Kim and Ron, as well as Shego and Dr. Drakken. Kim and Ron remember their first Halloween together; take a wild guess which one wore a cowboy outfit and which one wore a tutu.
Mass Hypnosis: Drakken tries this, using shampoo of all things, and a scheme involving teens MP3 players that didn't work out. The Seniors try it with a love ray.
Meaningless Villain Victory: Drakken steals the royalty money Ron gets for inventing the Naco. After Kim fails to get it back, he spends it on a giant laser that doesn't work as expected and destroys itself and his lab.
Memento MacGuffin: Ron's titanium-reinforced belt helped Kim remember that they were dating in "Clean Slate".
Merry Christmas in Gotham: Ron tries to take on Drakken by himself so Kim can have a nice Christmas with her family. Ends up with Ron and Drakken bonding over an old TV show, whose theme they sing together. Now, Kim Possible isn't exactly dark and edgy to begin with, but they were shooting for Lighter and Softer than usual.
Missed the Call: Kim initially set up her website looking for ordinary teenager jobs like babysitting, but got drawn into adventuring after a rescue call to Team Impossible accidentally reached her instead.
Motive Decay: The Mathter; He went from terrorizing Go City to making Ron his personal archenemy just because he used a variable (saying his tape recorder cost twenty dollars) in less than two minutes after they first meet. That's got to be some sort of record. This, like everything else in the series, is also lampshaded.
Ron: Oh great, now the math guy's back! Kim: And he's not even our villain!
Mood-Swinger: Doctor Drakken can be ranting with malicious glee about destroying his teenage foe one minute, and then switch to looking for milk in a supermarket. The "Moodulator" chips make Kim and Shego act this way too.
Amazingly, it was also inverted in that same episode, since Dr. Drakken wiped the floor with both Kim Possible and a Charles Atlas Superpower Monique. After beating them, Shego gloats, making Ron mad. Big Mistake.
Usually, Kim: perfectly willing and able to knock down men twice her size. Even discussed when she and Shego faced two huge wrestlers while Trapped in TV Land; "Well, this shouldn't be a problem."
Ron and Drakken's henchmen wear muscle-enhancing rings in "Ron The Man", but it's still Kim and Shego doing most of the fighting, maybe even more than usual.
Mystery Meat: Frequently served at Middleton High's cafeteria, to the disgust of the students. One episode had Kim and her class forced to watch a video saying what exactly went into Mystery Meat; the class ran out screaming and wanting to vomit.
In another episode, Wade analyzed the gravy that a ghost actually Sensei's astral projection used to write a message to Ron on the cafeteria wall. Wade told Kim and Monique that they do not want to know what's in it until they graduate. From college.
Nanomachines: The Nano-Tick in "Tick, Tick, Tick" (though it's not really on a nano-scale - according to Drakken, it just sounds cooler that way) and probably the source of Camille Leon's shapeshifting ability.
New Job Episode: Played straight in "Bueno Nacho". Subverted and played straight in "The Big Job"
The Seniors would have been content to be rich and eccentric, if Ron hadn't accidentally convinced them that Evil Is Cool.
Monkey Fist wouldn't have realized "the infant" who beat him earlier was "The Han" he was looking for...especially if Kim hadn't tried to insult his intelligence by mentioning Hana "Han" Stoppable was Ron's sister.
Barkin: And don't let them tell you they're supposed to have class outside! We put stop to that after the jellyfish incident. Miss Go: Oh that's so nice! You took the class to the beach! Barkin: No beach. Just jellyfish. Don't ask.
Kim: Like that time you cleaned your room. Ron: We agreed never to speak of that dark day.
There was also the "paper machete" incident. Not paper mache, machete.
Kim and Ron also tend to hitch rides from people whom they have helped in the past, often in some spectacular fashion. They do this a lot. Although a few of their rides do have Call Backs on previous episodes.
Supposedly, he also saved the world once, if his speech to Ron about graduation is any indication;
Barkin: Ah, Senior Year, I remember it well. Best two years of my life; big man on the football team [...] dated the most popular girl in school [...] I even helped save the world a time or two. Ron: Right on- wait, what?! You?
Not Me This Time: When Kim finds out that Dr. Drakken has been broken out of prison by a woman with "green energy blasts", she naturally drops in on his sidekick Shego, only to find out later that it was actually an alien who did it.
Shego: I'm. On. Vacation! Ron: So, it wasn't you that busted out Drakken? Shego: Who do you think I'm vacationing from?
Also done in the first part of the two-parter series finale, "Graduation Part 1". When several golf courses were undergoing eruptions, Kim Possible suspects Duff Killigan for the event. When confronted with the issue, Killigan explains that he wasn't involved, and even takes it a step further to reveal that his own golf course was defaced in a similar manner.
Also done in "Gorilla Fist" where Ron and Yori go looking for Monkey Fist thinking he kidnapped Yori's Sensei, not knowing it was a Batman Gambit by DNAmy. When found, Monkey Fist explains he wouldn't kidnap him because he was of no value to him.
Not so Above It All: A common gag. In general, it's a running theme in the show that Kim is nowhere near as infallible in her regular life as she is in "mission mode".
Not so Dire: A fair number of episode teasers establish an apparent crisis, only to reveal that the real sitch is relatively benign.
Not What It Looks Like: "Homecoming Upset". Bonnie forces Ron into a kiss just as Kim arrives on the scene. After getting over the shock of the sight, a very pissed off Kim has to be reassured by Ron that he was the "kissee" and not the "kisser" in the situation. Turns out, Kim is well aware of this, but she's still angry all the same.
Kim: No kidding! It took ya twelve stinkin' years to kiss me!
"Ill Suited", where Ron is trying to explain why he stole Kim's battlesuit.
Ron: Wait wait! It's not what you think! Kim: Oh? So you're not a cheater, a liar and a thief?! Ron: ... OK, it is what you think.
Oblivious to Love: Ron was completely oblivious of Cheerleader Tara's crush on him until it was too late.
He was also oblivious to Yori's also. This led him to tell Kim (who's developing feelings for Ron) that girls should just say how they feel.
Official Couple: Kim and Ron, from So The Drama onward. Word of God is they were planned from the start, which is unsurprising. Word of God goes on to further state that if there were any doubts, their relationship from "Graduation" onwards will indeed continue and flourish. More specifically that they will be together forever.
Bonnie and Senor Senior Jr. from "Homecoming Upset" onwards.
Dr. Drakken and Shego are strongly implied to be this, as per the end of "Graduation".
One-Winged Angel: Gleefully subverted; Drakken is mutated by one of his own chemicals, but it makes him even less threatening. Played straight, again by Drakken, later in the same episode.
Open Minded Parents: The Possibles, natch. Kim can go halfway around the world, battle giant robots, and get lost in time and space (maybe all three at once), yet her parents won't bat an eye. But she better not be seeing any boys...!
Out-of-Context Eavesdropping: Ron Stoppable breaks into his girlfriend's house, then her closet, steals her super battle suit, joins the football team as star quarterback, gets caught with the suit and controlled by a villain, ends up in a physical and emotional fight with Kim, then ends up on the team anyway (and is still a star player just in a different position), all because he thought Kim was going to take Bonnie's advice about "trading up" to a socially acceptable jock boyfriend. Ron then overheard Kim talking with Monique about trading up and agreeing with Bonnie. Turns out they were talking about a new mobile phone.
Perplexing Plurals: In "Naked Genius", Drakken captured Ron (thinking he got the brainpower he was after instead of Rufus) and forced him to build a doomsday device or else he'd be sleeping with the "fishes". He then gets confused if that is correct and asks Shego. Shego tells him that both fishes and fish are correct plurals for the word.
Personality Swap: Ron and Drakken swap their "good" and "evil" essences in one episode.
Pet the Dog: Shego with Junior, noteable in the second episode with them because this was around the time she descended into Stupid Evil territory.
Drakken: Aye. Set the mainsail, wench. Shego: Okay, first of all we don't have any sails. Second of all, call me 'wench' again and we'll be planning a burial at sea. Drakken:(nervously) Yearr. Arrgh.
Plot Parallel: Often found between the "basic average girl" and "here to save the world" plots of any given episode. For instance, Seņor Senior Senior's controlling attitude toward Junior's disco in "Coach Possible" showed Kim the error of her overzealous approach in coaching the soccer team.
Recurring Extra: The Middleton High students milling around in the background when Kim and Ron are at school are quite consistent, but fans particularly picked up on two: a freckled brunette usually wearing blue outfits and thus dubbed "Girl in Blue" and a tall, short-haired girl who fit the image of a Butch Lesbian and was dubbed "Alex Sapphic", first by slashficers, then by the fandom in general.
Red Shirt: Parodied in season three, in the Trapped In TV Land episode called "Dimension Twist", when Kim is temporarily sent to a Star Trek-esque TV show and appears in a red uniform:
Wade:This is the part of the show where they pick series regulars to go on a mission. Just make sure you're not the one wearing... Kim: ... A red shirt? Pseudo-Kirk: And... (to Kim) you! You're expendable.
Also, Drakken's hapless rank-and-file henchmen are dressed in red, and are as close to Red Shirt status as it gets in a Non-Lethal Warfare setting.
Ron losing his pants, which he started to lampshade. In the first season, upon seeing an enormous obstacle/opponent that they would have to face, he would often exclaim:
Ron: That would be so cool if it wasn't gonna hurt us!
Ron being 'micro chipped' by Wade.
As stated above, the number of almost kisses between Kim and Ron became a gag in season 4. However, if you're a K/R fan, you might see it as a Moment Killer.
Motor Ed's verbal tic. Seriously.
After "Rappin' Drakken," that plan's horrific failure becomes a running gag that spans Season 4 - mostly via Shego's snark or someone only remembering him because of the shampoo. This culminates in him being able to easily put together a Mass Hypnosis plan because "there was plenty of the mind control shampoo left over."
Several episodes, particularly the ones with two shorts that were more humor related instead of one full story, have the running gag of Kim getting stuck with the worst luck or having a much harder time dealing with something while Ron skates through the sitch with good luck and a total lack of interest. This includes Ron being bumped up to first class on a commercial flight - twice - while Kim is stuck in coach (Ron has the decency to try to pretend it wasn't awesome, though he fails), Kim being totally blindsided and humiliated by having the tell the truth all the time while it makes Ron instantly popular, Ron bonding with an overgrown roach monster while Kim is so grossed out she constantly freaks out (after telling Ron not to worry about bugs, no less), both episodes that focus on Felix and the first half of "Sick Day."