Metalocalypse inverts it: Toki Wartooth, Dethklok's rhythm guitarist and almost-literal second-fiddle to Skwisgaar Skwigelf, has an entire episode devoted to his inability to play the guitar. However, the only time we actually hear him play during the episode, he's upstaging Skwisgaar during a concert and doing a good enough job of it to threaten his confidence. The rest of the time, he's not as good as Skwisgaar and there is considerable distance between them in terms of skill, but he's still the world's second-fastest guitarist.
Professor Dementor from Kim Possible is said to be such a great villain that compared to him Dr. Drakken is even more of a joke. (Though at least Dementor invents his own doomsday devices.) But in the end he's foiled just as easily as Drakken, sometimes even more easily.
The Robotboy equivalent of Dr. Dementor is General Yakitori, who is supposed to be a greater villain than Big Bad Dr. Kamikazi. He won the "Evil Genius of the Year" award six times in a row, yet he's never been seen to do much evil. Or much genius, for that matter.
Total Drama Island characters have tons of these, since most characters don't get much screen time, but their character bios reveal many abilities that the fans have yet to see in action:
Ezekiel is apparently rather intelligent, since his bio mentions him speaking eight languages and winning the National Spelling Bee.
Cody and Lindsay are actually rich - this has never been mentioned within the show, although it explains why neither of them are that determined to win the prize money.
Gwen is said to love her family very deeply and apparently become "Soft as a marshmallow" around them, but she never mentions them, despite being away from her family far longer than most of the campers were.
Trent apparently loves motorbikes to such an extent that it even overshadows his love of music and spends almost all his time working on them. He never even says motorbike on-screen, though his love of music comes up often.
This is played for laughs in the Codename: Kids Next Door movie "Operation: Z.E.R.O." At the beginning in the museum scene, Numbuh One is surrounded by four enemies, and he excitedly says that now he has a chance to use his new move where he takes out four opponents in one blow. However, the villains retreat before he can do so. Later in the movie, when he's surrounded by his four teammates (who've been turned into senior citizombies) he says, frightened, "I wanted a chance to use my new move where I take out four opponents in one blow, but not on you guys!" End result, unfortunately, the viewers never see this new move of his.
Inversion in Home Movies. Especially in the last season, everyone criticizes the main character's movies as being horrible, but they're actually pretty good, even by adult standards - and the characters doing them are pre-teens.
Parodied during the episode "Peterotica", where Peter writes pornographic novels. Everyone absolutely loves them, and they become a major hit, which would normally leave the audience wondering how Peter could possibly write anything halfway readable; however, the episode takes every possible opportunity to read excerpts from Peter's work, confirming that his writing is, in fact, downright abysmal. One book is entitled "The Hot Chick Who Was Italian Or Maybe Some Kind of Spanish."
Averted with Meg's singing. Mila Kunis is, by her own admission, a terrible singer, so Tara Strong took over when Meg actually had to sing.
Also, during the episode "420", after Brian succeeds in legalizing pot, he goes on a rant about how crime is almost nonexistent and productivity at work skyrocketed. However, with the possible exception of Ollie Williams, all we see are people so stoned that they can't do their jobs properly. Perhaps the people gathering the statistics were too stoned to do their jobs properly, so they pulled the numbers out of their asses.
Raven from Teen Titans, the Emotionless Girl, was said to have to be emotionless to prevent her powers from going out of control. This was shown precisely twice, with most of the series showing her expressing varying degrees of emotion (and even falling in love in one episode) with no apparent problem. She did become a more developed character for it, albeit by ignoring the limitation instead of finding ways to work around it.
The show devoted two episodes to his future persona Ben 10,000, who was established as having obtained that many alien forms on the Omnitrix. Between the two episodes, he and his son use fewer than twenty of them total, and only three couldn't be found on Ben's watch in the present day. And that's ignoring thesequels...
Several of Ben's aliens are stated in their official profiles to have abilities that are never shown in the series, such as Wildmutt being able to fire spikes from his back (supposedly Ben's form isn't mature enough, but other members of Wildmutt's species have been shown who still didn't do it), Jetray being able to breath underwater, and the list goes on. Ghostfreak's telekinesis was one in the first series, but Alien Force eventually had an episode with him using it.
Humongousaur's ability to grow bigger wasn't originally one in Ben 10: Alien Force, but became one in later episodes due to the writers apparently forgetting he could do that. Despite the fact it was his main power when he was first introduced.
Vilgax, when coming back in Alien Force, is stated to have absorbed the powers and equipments of 10 great heroes. He uses around five of them for all the time he had those powers.
The new Omnitrix, despite supposedly being better then the previous ones...isn't.
Galvans, Grey Matter's species, are said to smarter than Cerebrocrustaceans, Brainstorm's species. Yet, Brainstorm has been shown running physicals calculations in his head and accurately predicting every move his opponents will make, while Grey Matter's intelligence has been limited to technology.
In an episode of Rocko's Modern Life, Rocko and Heffer have to watch over Filburt's pet mynah bird Turdy, whom he claims has a beautiful singing voice. All he does through the episode is squawk. Played with in that Filburt loved that bird, despite it being an obvious pest.
Played for laughs in one episode, where the window wipers of the car from Knight Rider were the most evil window wipers in the world. It just didn't come up much in the show.
Wonderfully parodied with Zapp Brannigan. He is constantly praised as a brilliant military leader and a brave fighter but all the main characters know that he is in fact deeply stupid, cowardly and incompetent as well as being a major jerkass who takes credit for others' work.
Inverted in the case of the lawyer who resembles a humanoid chicken who calls himself "just a simple hyperchicken from a backwoods asteroid." (A deleted scene from Into The Wild Green Yonder, reveals his name to be "Matcluck".) While supposedly incompetent as a lawyer (when arguing an insanity defense, he claimed, "well for starters, they hired me as their lawyer") he has a perfect record on-screen (two successful defenses, two successful prosecutions. He even managed to negotiate a sweet deal for Bender while under arrest himself, "awaitin' trial for that there incompetence."
Played for laughs in one episode, "Lisa's Wedding" where Lisa's first love (or at least, first fiancé) is introduced, in which Hibbert comments of Maggie, "She's quite a hellion but she does have an incredible voice." The closest thing she ever got to saying anything on screen was when Marge interrupted her when she spoke with her mouth full. (Or for that matter, immediately after Hibbert's quote, where said fiancé cuts her off when she's asked to sing.)
"Will that girl ever shut up?"
In another future episode, Maggie is revealed to be a world-famous singer. She still doesn't use her voice because she's pregnant and talking at that point could be bad for the baby, according to her doctor.
Further in The Simpsons Lisa Simpson is often referenced as a skeptic (mostly by herself however, so this could be construed as the character's obliviousness). However, the character is also shown to at various times show faith in Christianity, Buddhism, (temporarily) Wicca and alternative medicine, showing rather extensive compartmentalization. On the other hand, a Western Christian converting to 'fashionable religions' such as Buddhism and Wicca and preferring alternative medicine while looking down on her peers would be very fitting stereotypical behavior for a pseudo-intellectual character.
At the end of the episode "Married to the Blob", Comic Book Guy states he found a new job after having closed his shop, thanks to his degree in Chemical Engineering. Said degree was never mentioned before and will likely never be mentioned again. Other episodes stated that he has a Master's degree in Folklore and Mythology.
In Animaniacs, Ralph the Guard is often seen chasing the three main characters around (often as part of a Funny Background Event) but never succeeds in catching them, at least onscreen. Still, given what some other characters say, he may be more successful in corralling them than these scenes suggest. (And he has delivered them to both Dr. Scratchnsniff and their teacher in crates.)
In one of the S1 episodes, Musa talks to two background students Ortensia and Priscilla about having to work together to save Alfea, letting drop that Ortensia has the best counterspell skills and that no one can fly as fast as Priscilla. Which would be nice for the final battle, except that, well, they're background characters. (In the original version, she only discusses how everyone has a part, without any abilities being mentioned.)
Another S1 ep has Flora mention before an exam that Musa gets the best grades out of the Winx.note Her exact words differ slightly... Original: "Give us a break, we all know you're a straight A student." 4K: "I'm sure you'll be fine. You've got the best grades out of all of us."It's a break from the usual expectation of having the tech whiz be the straight A student, but not only do the writers never use this fact, at least one scene actually seems to be inconsistent with it (read main post, then 2nd reply).note The part with Musa attending Griselda's class. Incidentally, the 4Kids dub of the scene in question doesn't have this problem, as the dialog goes: "I competed in the All-Realm Magic Games. In fact, I was the first female black belt gold medalist." "And what year was that?" "It was 20 years ago, but I can still fight like a champion!" Point is, the writers have never done anything that would require Musa to really show off her smarts.
In the original, Flora also got top grades; when it was translated, Musa was the only one mentioned (which might be a little racist, since she seems to be the Magix equivalent of Asian).
One or two episodes have kids mention Stan's mom having large breasts. The way she's animated, she actually looks completely flat-chested most of the time.
Another episode has Butters make construction paper models of the main cast which, unsurprisingly, look exactly like them. Kyle then comments that they were slightly inaccurate, as his nose is shaped differently (neither he nor the model have a visible nose) and Stan's eyes are blue (each have black dots for pupils).
There are several other episodes where they play with this. In "The List," for example, Gerald says Kyle has his mother's nose; again, he has no visible nose, yet acts horrified since his mother's nose is somewhat large and ugly. "The Coon" would probably count as another example, merely because the characters can tell Mysterion's face apart from anybody else's while the audience can't.
Ugly Bob in "Terrance and Phillip in Not Without My Anus" apparently has a face which looks as if "somebody tried to put out a forest fire with a screwdriver" though he's animated to look like every other Canadian. A later episode makes it clear that Americans can't tell the difference, while other Canadians (and Saddam Hussein) can.
In Teenage Mutant Ninja Turtles (1987), Shredder's ally Krang had a massive mobile fortress called the Technodrome, supposedly one of the most powerful weapons in the universe. It was largely reduced to MacGuffin status, with occasional plots to recover it from wherever the hell it ended up after their previous attempt to get it to the surface of the Earth. Due to the short episodes, it typically took less than five minutes to be defeated the handful of times it actually got there; since "powering the Technodrome" was Shredder's default motive for doing anything, this was often five minutes after an entire series of trying to get it moving.
On The Smurfs, Gargamel's cruel godfather Lord Balthazar is supposedly a far-more competent wizard than his godson. However, he's never seen using any actual sorcery, using machines, technology, and other scientific experiments to achieve his goals. Practically every other wizard in the series, Gargamel included, has displayed far more magical knowledge and skill than Balthazar, with Balthazar dismissing almost anything mysterious or magical as "nonsense" or "fairy tales", even though it is plainly visible. In fact, his "magic wand of the future" is actually a musket.
A running gag is for characters to make note of Boomhauer's suave and charming way with words. This is never apparent to the viewers, as Boomhauer speaks in unintelligible mumbles.
In one episode he takes a heartbroken Bobby under his wing, and you see that Boomhauer's technique is the "shotgun approach" (put enough lead in the air and you're bound to hit something): he hits on every attractive woman he meets and gets rejected nine times out of ten, but he focuses on the one who says "yes" rather than the nine who say "no".
We do get to see his eloquence when the scene is shown from his point of view, showing Boomhauer speaking normally while everyone else has his Motor Mouth tendancies
Transformers Animated: According to supplementary materials, Grimlock is equal in power to Megatron. While Megatron is portrayed as a huge badass that can utterly thrash all five main Autobots at first, Grimlock is frequently tossed around by lesser opponents. There was actually going to be a scene in the first season finale where the two met face-to-face, and Megatron mopped the floor with Grimlock and the other Dinobots. (It ended up being cut due to bad animation and the realization Grimlock fans wouldn't like it.) Though power does not necessarily equate skill. Megatron is a several million year old war general in an army where Asskicking Equals Authority, while Grimlock has a very underdeveloped mind and is only a few months old.
Transformers Generation One has plenty of characters with traits mentioned only in their bios. To give an example: Thundercracker is supposed to be a Noble Demon who uses sonic booms, and Skywarp is a thuggish prankster with the power to teleport. You'd never know it from the show, where they were almost always just Those Two Bad Guys who flew in the background and shot at things. There was even an episode where Megatron stole their powers, during which he uses them more in a single fight scene than they had in the entire series.
Predaking is treated as one of the most threatening opponents in the entire series. His official bio notes that "as a warrior he has no equal; as a weapon he has no restraints. He is the closest thing to a perfect fighting machine the Decepticons have", claiming him to be the most skilled and dangerous of all the combiners and possessing no weaknesses except that his allies are terrified of him. He has one of the worst combat records of any character in the franchise, and never won a battle onscreen in the original series - and it's not even that he gets beaten by outwitting him or exploiting his weaknesses, no; he's been straight-up overpowered by everything from other combiners to Sky Lynx on multiple occasions. And if you count Transformers Headmasters, he was once taken down in one shot by Pointblank. Who's Pointblank? Exactly.
In Generator Rex Providence's Red Shirt Army gets a whole episode about how each officer is put through Training from Hell in order to be top class officers to fight the EVOs that are infesting the world. Problem is the officers of Providence have largely been shown throughout the series as useless with in dealing with any EVO by themselves without the help of the superpowered Rex or Badass Normal Six. However it is suggested that if Rex or Six is their Godzilla Threshold with Evos they can't handle themselves.
Col. Stinkmeaner on The Boondocks is an inversion: he's a blind man who can drive a car perfectly parallel to the road, detect objects in front of him (even while in the car), beat up Granddad and experiences no inconvenience as a result of his blindness, which Huey attributed to him having the Disability Superpower of radar-vision. Then he's revealed to not have any such ability; he just got lucky during his fight with Granddad who beats him in a rematch, accidentally killing him. and no credible explanation is given for how he could drive regularly without attracting any police attention. Unfortunately, he learns Kung-Fu in Hell and it turns out he hung out with a Badass Crew of Evil Old Folks.
The Redakai TV series seems to be relying on its website to give us our characterisation, one of which is that the character Zane, is the only one capable of defeating the hero Ky in straight combat. It hasn't happened yet and the character biography is so far the only indicator this could happen. The sheer amount of ignoring Show, Don't Tell in this show is just one of its many shortcomings.
In Batman Beyond, the assassin Curare was supposedly the best member of the League of Assassins, the best organization of hired killers; none of them were ever known to have failed to kill a mark; of course, after Curare - the supposed best - was the first to do so when she ran afoul of Batman, she was targeted by the others herself, and she proceeded to wipe out the whole organization, only to fail a second time when she went after Batman. In short, the only known victims of this "most successful assassin" were other members of her organization, which brings their actual skill into question.
Jetta from Jem is introduced as a saxophonist and her introduction song "I Like Your Style" clearly shows her using it. Despite being told she's the sax player of the group, she only uses it in two other Misfits songs ("Trapped" and "Free and Easy"). Otherwise she just provides backup vocals and plays a guitar. The fact that she was originally a bass guitarist and the fact a sax changes the music vastly could be why she rarely plays the saxophone.
Greg Universe in Steven Universe is intended to be an excellent musician held back from a successful career by his exploitative manager. While he's a talented guitarist and good at the technical side of things, his singing voice is at best rough and his Signature Song, "Like A Comet," has a clear autotune. Ironically, his voice actor, Tom Scharpling, is one of the few among the voice cast who doesn't have some kind of musical career, which makes Greg's voice stick out somewhat from what's otherwise a murderer's row of singers. It's particularly noticeable when he has a duet with Rose, who is played by Broadway actress Susan Egan.
In Justice League there's dialogue referring to the notion that Superman is virtually invulnerable and significantly stronger than the other Leaguers, even though the show famously nerfed him so that he wasn't particularly powerful in the grand scheme of things, because if he really was that strong, it wouldn't make sense to even have the rest of the League at all.