Mm-hmm... okay... say, can you talk a bit slower? I'm trying to take notes.
Baron von Helsingard: I see not only through the senses built into my own armor, but those of my every soldier. Atomic Robo: You know what I've always liked about you, Helsie? You keep telling me how to beat you!
In Rave Master, this happens quite a bit in the manga, mostly when new moves are introduced to the audience. Possibly deconstructed during the fight with Doryu when Ruby, explaining to our heroes how innate magical alignments work, accidentally reveals the alignments of the heroes to the bad guy. His saving grace was that he changed their alignment to Dark earlier, making the information useless.
In Berserk, Guts is fighting a regenerating demon whose wounds heal as fast as they're inflicted. The demon taunts him by saying that it can regenerate endlessly as long as its head is intact. Guts chops the demon's head in half and thanks it for telling him.
Bleach. A manga that models its fights on old-fashioned fighting styles where the verbal warfare in a fight was even more important than the physical aspect absolutely revels in this trope as characters vie for a balance between cowing an opponent with the mere thought of confronting the power they possess and revealing so much the game is up before it's even started. Sometimes, character fail spectacularly to get the balance right. At other times, they make this trope look good.
First, because most of the series revolves around this, is Aizen. His power is unbreakable, near absolute hypnosis and sense controlnote as long as he's telling the truth about it, as even as broken as we've seen, it could be worse that can be used against anyone who has seen him release his sword. Everyone in the series has seen his release except for the humans (only Ichigo and Orihime matter anyway). He even did lie about his ability to reach that point, saying its power was to cause enemies to attack each other, by using water and fog, or some crap. All of this could be faked by his actual ability. Before he made his Villain Exit Stage Left, he told his enemies his ability. He had no intention of killing them, and was pretty much just gloating.
Hirako Shinji, whose powers reverse his opponents' senses and movements (left=right, up=down, and all that), explains exactly how he does so, though he later revealed that he was leaving some vital information outnote specifically, that he can also switch up front and back, and that he can switch only some directions without given any clue as to which ones are switched at the moment in an attempt to throw his opponent off the track. It doesn't work.
It's even worse than that. Shinji basically said that not even Aizen could possibly invert his whole visual-spacial perception on the fly. It's borderline hilarious when Aizen does just that with almost no effort.
Later, Shinji explains the basics of his powers again, when fighting Bambietta Basterbine. Bambietta doesn't gain any particular advantage from this since her next move would've worked just as well without any info about his powers. She points out that it doesn't matter if she knows where her opponent really is, because she can just blow upeverything.
Gin tries the same thing — explain one aspect of the powers, but neglect to mention another aspect so it'll catch the opponent completely by surprise. It fails even more completely, as his opponent almost immediately realizes that Gin was leaving something out, and then almost immediately figures out what that was.
Although later, it's revealed that he was actually keeping another ability secret... for use against Aizen. Of course, we all know how this is going to go...
Gin didn't keep an ability secret, he flat out lied about what his Zanpakutou's ability is. In fact, this worked as perfectly as he planned it to, and even Aizen, who was on the receiving end of Gin's savvy, thought the attack was going to kill him. It didn't, because the Hougyoku's got more power than either of them thought.
Largely averted by Kyouraku, Ukitake, and Starrk. When Starrk wonders how Ukitake seems to fire a Cero at him he's told to work it out for himself. Neither Stark nor Kyouraku bother—at that stage—to explicitly state what their skills are either, only to make observations and assumptions about each other. Naturally, some of this backfires on both parties.
All Kyoraku tells Starrk is how to play the colour games, and that may be justified if he is bound by the "rules" to let Starrk have his turn, and also perhaps because he was trying to give Starrk a chance without actually giving him too much of an advantage. After all, it's very clear he intends to kill the Espada from the word go, he just doesn't necessarily want to.
Zommari spends all of his fight with Byakuya explaining how his powers work. In very long-winded speeches. This is lampshaded by Byakuya himself: "You should be ashamed. Before my eyes, without wasting any time, you revealed your entire hand to me". What a pity Zommari didn't pay attention—but then again, he was also supposed to represent the curse of intoxication, and he was intoxicated by both Aizen's and his own power.
Every time Izuru Kira fights an enemy, he feels the need to explain Wabisuke's ability to double the weight of his target every time he hits. Every single time. Not that he gets many fights to begin with...
Kira usually doesn't explain it until he's already affected them. However, the only canon fights in which he's used this sword were against Rangiku, who was immune once she released her own sword, and Avirama Redder, who was designed to be susceptible as he was a bird who attacked and defended with his wings.
Averted with Yumichika as well. Yumichika never even introduces his name to anyone he fights, let alone his real power. He once admitted he had a kido-based secret before unleashing his power but didn't describe the power itself. The second time he used it, he didn't offer any explanation at all until his flowers were already budding and by then, there was only just enough time for him to explain his power before his opponent died.
Sui-Feng always explains that her weapon kills in two strikes. Lampshaded when Ggio Vega dodges her attacks and calls her a fool for warning him. It turns out to be an example of psyching out the enemy, as she was only testing him to see what an arrancar's power was like. Once she'd seen enough she promptly revealed she'd hidden certain aspects of her shikai, such as the requirement for two hits not being limited to striking the same place outside the body as long the two stabs were able to cross each other inside the body, creating a two-hit strike internally instead of externally.
Ulquiorra gets a prize for explaining his Regeneration, a basic skill in anime, and none of the other, more important abilities.And he explains his regeneration to a monster that possibly doesn't even know what he's saying! This stands out simply because he chooses to explain how he can recover eyes and limbs, and yet he never explains how he gained his second form, if his lances are unstable, and how he hid this form for X amount of years.
Parodied in the Vandenreich arc, where one of the Stern Ritter, Berenice Gabrielli, was killed (offscreen) because she kept talking about her powers instead of defending herself. While fighting Kenpachi Zaraki. Who was deaf at the time. Hence we don't even know what her power was. Parodied again when another Stern Ritter, Shaz Domino, starts to brag about his powers, but Ichigo blasts him with a Getsuga Tensho and moves on before he could say anything about it.
Yamamoto explains what his bankai does, but in his case, he can afford to because there's really nothing an opponent can do to counter a 15-million-degree Flaming Sword and Battle Aura except Run or Die. He also doesn't say anything about how it actually works or of any potential weaknesses.
Meanwhile, Rose has a moment right up there with Shinji. Rose's Bankai, Kinshara Butōdan, has the ability to generate illusions through sound that the mind makes real. While he's doing this, he completely outlines what his power is to Mask de Masculine, ensuring the man renders himself deaf, and leaving Rose dying on the ground. Well done, Rose, well done.
Guenael Lee constantly explains his ability, The Vanishing Point. In his case, he can afford to because The Vanishing Point makes him invisible and constantly erases his opponents' memories, so they forget all about him even while exchanging blows. Though it does raise the question of why you would explain to people your power of being able to make them forget your explanation.
Gremmy Thoumeax explains how his power works with each attack, explaining that he "imagines" something and it becomes true. This comes off as extremely smug, as he waits until after he's used his ability to explain why his victim's attack failed or why their bones are now made of cookies. The habit ends up backfiring when he No Sells an attack by Kenpachi and explains he imagined his body was harder than steel. He's cut off mid-sentence when Kenpachi adjusts his attack's strength so he can cut through steel, slicing Gremmy.
Inverted with most other Contractors: They don't explain their powers, but they do explain their remunerations. Oddly, Contractors are surprisingly compassionate regarding each other's remunerations, so this is usually a good idea. Telling your captors you need a cigarette nets you a cigarette.
This is usually a case of Pragmatic Villainy, however, as contractors who don't get their remuneration suffer Power Incontinence and become dangerous to everyone (and The Masquerade) very quickly. Contractors who really have it in for each other have no shame in exploiting the other's remuneration to catch them off-guard.
Gohan has proven that Cell is no match for him in Dragon Ball Z. After a bit of a beat down, Cell decides it is best to cut his losses and self-destruct himself and take the planet with him. The process takes about 60 seconds, in which time Cell explains exactly what he is doing and helpfully adds that attacking him will make him explode faster. This gives Goku enough time to figure out what to do with Cell and even say a few goodbyes before teleporting Cell and himself off planet.
The fourth episode of Katanagatari was basically one long string of this, with four characters involved in the fight.
Though in Nanami's case, it's justified in that she's basically invulnerable and has absolutely nothing to lose by taunting her opponents with her powers. Also, she's a Death Seeker on top of that, though those opponents aren't even remotely capable of killing her.
Naruto has some of this as well (such as Sakon and Ukon explaining their powers to Kiba) as well as some subversions (like Kakashi lying to Zabuza about how the Sharingan works). Most of the time though, it's subverted: though there is an awful lot of exposition about how various powers and attacks work, its usually done inside someone's head as they study an opponent's attacks and strategies or as dialogue between teammates sharing info on an enemy's technique.
Averted during the battle between Rock Lee and Gaara. Naruto, who eventually goes on to fight Gaara, asks Gaara's teammate Kankuro if Gaara's armor has any weaknesses. Kankuro refuses to admit that it does, but thinks to himself that as it takes a considerable amount of chakra and weighs Gaara down, Gaara must be desperate if he has resorted to using it.
Most of Akatsuki averts this, too, and most of the time it becomes a plot point where the good guys have to figure out what their powers are and how to beat them. It's usually played straight after the good guys have guessed the villains powers right, and then the villain commonly has an exposition including the details they left out, though.
Pain, in particular, didn't say a goddamn thing about how his powers worked and Konoha had to figure it all out on their own. Tobi, as much as he likes to talk about his plans, was also pretty mum on how exactly his powers work.
An interesting variation occurred in the Sasuke vs. Danzo battle, where Sasuke, after a few minutes of fighting, exposited the weaknesses of Danzo's technique, the reality warping Izanagi. Danzo replies with "So you figured it out", to which Sasuke, in turn, responds that, yes, now that Danzo has confirmed that Sasuke's guess was correct, he has figured it out.
Kabuto, however, explained the Impure World Resurrection technique in detail to Tobi. Of course, Kabuto's generally pretty Genre Savvy, so his explanation might be wildly inaccurate; at the very least he almost certainly left out a few critical details. Kabuto didn't really volunteer the information, either; Tobi threatened not to meet his end of the bargain if Kabuto refused to tell him how the technique worked.
Kabuto didn't have a problem with explaining it to Tobi, because there was nothing Tobi could do with the knowledge. Even killing Kabuto on the spot wouldn't stop the technique; the zombies would keep carrying out the last order they'd been given, or acting independently if they'd been allowed to do so. The only way to stop it was to know the specific deactivation sequence.
Justified when some of the reanimated ninja, their personalities still active, describe their abilities to their enemies, as they want their enemies to win. Unfortunately, due to a combination of being unable to control their actions and being too awesome, it doesn't quite work.
One Piece characters will either have this, a sideline character, or a handy-dandy side panel to explain new Devil's Fruit abilities.
Even parodied in-series with Kalifa and Nami. Kalifa brags that she is keeping her Devil Fruit name a secret... only for Nami to guess it right away. Played straight later in the battle (and very necessarily, because that was one weird power): to wash away others' powers, curve, and distinguishing features such as fingers for holding weapons.
One minor Baroque Works member tries to explain her "Kilo Kilo" weight-altering ability and how she uses it in combat, but no one pays her any attention.
Crocodile was confident enough to explain his sand powers to Luffy, adding that he's spent years refining his abilities and figuring out the creative uses for it. Justified as he was fighting Luffy in the desert, where Luffy had zero chance of winning, and he has mastered his abilities to the point he can "dry" anything with his left hand, causing almost immediate death and capable of creating another desert. Luffy was lucky to have live long enough to figure out his weakness, much less beat him.
The 'handy-dandy side panel' sees heavy use in Impel Down, which sees characters that hadn't been seen for a long time return, to provide quick refreshers on their powers.
When Luffy fights Blueno for the second time, Blueno is all too eager to explain his Devil Fruit powers.
One Piece is also a less egregious example than most, as Devil Fruit powers provide one-of-a-kind and/or incredibly unusual powers, and it's unlikely than a person will know about any given fruit's powers without either having it themselves or knowing of the person who does already. Also, such characters tend to explain their powers by stating the vague concept behind those powers (Kuma's power "To push anything" being a good example), but don't explain the various creative applications they've figured out to weaponize that vague concept until the enemy has already gotten a good taste of them.
The only time this didn't pan out so well was when Sanji, who researched an invisibility-granting fruit extensively in hopes of gaining it's power to use for perverted reasons someday, had to fight Absalom, who got it (for the same reasons) first.
Luffy and Chopper will sometimes ask the enemy to explain their powers, and the enemy will often oblige.
Parodied in Luffy's fight with Enel: Enel's in a bit of a pickle because of Elemental Rock-Paper-Scissors against a substance he's never even come across: rubber, much less met a Rubber Man. Being Enel, after regaining his composure, he immediately figures out that Luffy is a Paramecia-type fruit user, unlike his Logia-type. So he reforms his staff into a trident and pierces his skin. He then boasts that he's worked out that Luffy still has physical weaknesses like being stabbed, which Luffy replies, "yeah". Nami gets annoyed that he told him this, and couldn't be bothered to bluff.
Nami's battle against Miss Doublefinger justifies it, since Nami had never used the Clima Tact (a Weather Control Machine that Usopp invented for her previously) before, and spends half the fight dodging attacks and the other half reading the manual to figure out how it works.
In Yu-Gi-Oh!, Pegasus explains the abilities of his "Millennium Eye" to Yugi, including the ability to read minds. This gives Yugi the chance to come up with a counter stratagem.
Let's just say this series uses this trope all the time when it comes to card effects and stop there.
This is actually a reversal from the real card game, in which you must allow your opponent to look at your in-play cards if they ask to do so, and you cannot prevent your opponent from looking in your graveyard either should they ask. Cards in your hand, deck, and face down are exceptions to this, however. A number of the villains' gambits count on the hero not knowing how the cards work.
This actually turned out to be rather helpful in the dub version, as instead of re-editing each scene involving cards to change the Japanese words into whatever language it's being dubbed in, the editors simply erased everything on the card and have the characters themselves explain what it does. (This was done because US law prohibits a TV show from directly advertising its own merchandise. Since the same cards seen on the show are also sold in real-life stores, they can only be shown in altered form.) While it does provoke some Fridge Logic, it does make some of the character's surprises more genuine (since they literally do not know what cards outside of their deck do).
In the anime, Yusuke is forced to fight someone in complete darkness. His opponent has a helmet-type device that allows him to perceive and alter the flow of energy around and inside him, letting him A) see in the dark (which Yusuke has no way of doing) and B) strengthening parts of his body temporarily. He explains all of this during the fight. The viewer is left screaming at the television for the opponent to just beat the shit out of Yusuke, which he can do with impunity thanks to the Night Vision Helmet.
For the most part, this is actually an averted trope. Explaining Your Powers To The Enemy, while it makes utterly no sense in-universe, is mainly used so the reader/viewer can understand the ability being used. In the anime, the narrator explains the abilities or items characters are using most of the time, and thus this trope stays averted for the most part.
Jojo's Bizarre Adventure is a repeat offender of this, as shown in the page image. Be they vampires, hamon/ripple fighters, pillar men, stand users or nazi cyborgs, the majority of fighters tend to face each other openly and gloat about their powers, abilities and strengths (and through them letting the opponent infer their weaknesses and limitations). Some characters avert or subvert it: Figuring out the effects of Dio's Stand was the primary concern of the heroes in Part 3, with Kakyoin performing a Heroic Sacrifice to relay the information to the others.
Part 3's Steely Dan, meanwhile, very quickly lets the heroes know what Lovers does. Reason: It's the perfect deterrent, especially since Jotaro, already disgusted with Dan killing off Enya,his own ally, had managed to give a sneak preview when he punched Dan—and in the process hurt Joseph. He still leaves out Lovers's ability to create decoys out of dead tissue.
The Law of Ueki loves this, either by Calling Your Attacks or just by plain showoff. But that's only for very powerful or very minor enemies. Figuring everybody else's powers and limitations often becomes a minor plot point. It certainly helps that Ueki is very good at figuring out their opponents' powers, and that equals victory.
In Hunter × Hunter, people can make techniques with self-imposed restrictions on them (for example, only being usable at certain times or against certain people). The more harsh the restriction, the more powerful the technique becomes. The Mad Bomber (Gethru) in the Greed Island arc of Hunter × Hunter, possibly being Genre Savvy, made his restriction be that he'd have to explain how his ability worked before using it.
His explanation had to include that he had to tell his opponent the explanation for the technique to work, which he did at the very end of his speech. A brilliant case of Lampshade Hanging, since at first it looked like a major mistake, as the information was even more useful to defend against the technique than usual.
It also helps that he can plant the bombs first without explaining. The first time he's shown using it, by the time he started explaining his powers, it was already too late to avoid it.
This series generally averts it: Unless they're just allies sparring (and even in those cases sometimes), characters will try their hardest not to explain their powers, including purposely using them in misleading ways or using only a narrow selection of their moves. Knowledge of someone else's powers is a frequent key to winning battles and can be used as bargaining tools outside of combat.
In Shaman King the X-Laws go to great lengths, sacrificing many of their number, to figure out what medium Hao is using to channel the Great Spirit of Fire so that they can destroy it. When Hao realises what they're after he says they could have just asked - he's using the oxygen in the air around him (since "a fire needs air to burn"). At which point the Crazy-Prepared X-Laws trap him in a barrier and detonate a grenade to use up all the oxygen in the enclosed space, suffocating the Spirit of Fire. It doesn't work, as the Spirit of Fire changes into Water.
Played with in NEEDLESS villains who do this usually get their asses kicked in a hurry. It actually takes the heroes quite a while to figure out how Saten's power works, even to the point where Blade can't use it after he memorizes it. On the other hand, Uten outright lies about his powers but is still defeated in the span of an episode.
Rosario + Vampire has just about every big bad of the week explain their own powers. This also applies to most of the protagonists.
During the Finals in Mobile Fighter G Gundam, each member of the Shuffle Alliance demonstrates his newly-developed Finishing Move to The Hero Domon before their official match, which lets him figure out how to counter them, including his developing three new attacksnote the God Shadow, God Slash Typhoon, and God Field Dash for the curious expressly intended to counter those moves. In this case, the Alliance is the Five-Man Band and Fire-Forged Friends (and Domon's their leader), so to them giving him a fair chance is the right thing to do even if it means they lose. It also helps that being defeated by Domon doesn't eliminate them from the tournament. The exception is Sai Saici (also the only member of the band who fought Domon to a draw instead of losing to him in the Preliminaries), who keeps his ultimate technique a secret until their match.
Also, Argo didn't explicitly show his move to Domon, but rather used it during other matches beforehand.
In Gamaran this trope is played but only for the sake of the audience: usually it works like this: character performs a seemingly pointless or very fast attack and, a small explanation of the technique is given. Other variations include the user "mentally explaining the attack" and the witnesses commenting on it.
In A Certain Magical Index, this is frequently subverted. While many people will happily explain how their power works, this is usually either unhelpful (Espers explain how they're doing something, but this rarely reveals what they can't do) or deliberately false.
Spoofed with the 7th Level 5, Gunha Sogiita. He often tries to explain how his powers work, only for someone nearby to say "That's completely wrong!", prompting him to respond "Well, then what the hell did I just do?" He actually has no idea how his powers work... and neither does anyone else (which frustrates the scientists studying him to no end).
As the page quote indicates, Atomic Robo's nemesis Lord Helsingard has a tendency to do this. In the first issue, Robo meets Baron von Helsingard right after Helsingard uses the Vril Organ to become an Energy Being. After effortlessly regenerating an arm, Helsingard brags while pointing to the organ implanted in his chest. As Robo puts it, he should change his name to "Baron von Blabs About His Only Weakness." (Notably, though, the scene with the page quote wasn't entirely a straight example... Helsingard gave Robo just enough information to goad Robo into a trap.)
Here's an example that's not about powers, but still fits the trope. In the Dick Tracy story "Crewy Lou", crime boss "The King" hides records of his activities in a watertight compartment under a filled water tank. Tracy susses this out when he finds photographs of the King standing by his tank with the water drained out. Now, why exactly did he take those photos?
So you have a cosmic gadget that has a singular Weaksauce Weakness. Okay, no big deal, just avoid those situations. Oh crap, something's come up that just happens to match... Okay so since you're going to have to think something up anyway, at least make that you're just improvising, not that - Oh no! My ring is useless against the color yellow! Hal, you idiot... Although it's not like the rest of the Corps are any better, you'd think that as a group of "interstellar super cops" they wouldn't go around telling everyone what color to paint their bullets.
Justified in that the Green Lantern Corps has had members like Sinestro go evil before, at which point the secret's out anyway.
Superboy (Kon-El version) was originally very prone to explaining how his tactile telekinesis worked because it had no visible effects that showed what it was and the writers wanted to emphasise that his powers weren't just a carbon copy of Superman's. Unusually for this trope, this didn't cause him many defeats, but it did cause his Young Justice teammates to make fun of him a lot.
Empowered told Thugboy how her suit works (NOT!) when they met first.
In X2: X-Men United, Pyro explains how his powers work to Magneto. That's right, tell the guy who controls magnetism that you're useless without your metal lighter. He does switch sides later on, but it still is pretty stupid to tell anyone how your powers work.
In X-Men: First Class, Shaw's nice enough to explain his energy-absorbing powers to Colonel Hendry (and the audience), even noting how they make him ageless, before promptly using them to turn Hendry into a human firecracker.
In Man of Steel when Superman's fighting General Zod in Smallville. Supes knocks Zod's helmet off which causes him to be overwhelmed by his enhanced senses. Superman then tells Zod how to overcome this while they were still fighting.
Hamilton: Let me say this as clearly as I can. You cannot beat me. I am a part of them. The Wolf, Ram, and Hart. Their strength flows through my veins. My blood is filled with their ancient power. Angel: Can you pick out the one word there you probably shouldn't have said? (he vamps out and bites Hamilton, draining his blood) Angel: Wow. You really are full of it!
Myths & Religion
Samson and Delilah: Samson has Super Strength because of his hair; but Delilah is a really hot Philistine chick. She asks him what his weakness is. He lies to her and she immediately tells her family who try this on him and it doesn't work. Then she pouts and tells him that she's upset he lied, and he lies again. She again tells her family who tries this and it doesn't work. She makes doe-eyes at him a third time and this time he tells her the truth and she tells her family and they weaken him and capture him. Samson wasn't very bright....
His hair isn't actually the source of his power (as any Bible scholar can explain) but because he'd broken every other rule God gave him. It has more to do with the fact that Samson finally crossed the line by breaking his vows as a Nazarite (seen here) that God revoked his strength.
Baldr's mother, Frigg had everything except mistletoe promise not to hurt him. Then, she told Loki (in disguise) about this weakness. After this, Loki had the blind god Hoor throw a mistletoe arrow at Baldr, killing him.
In Portal 2, the Final Boss goes on an extensive rant near the beginning of the fight explaining precisely how he will not repeat the mistakes made by his predecessor, along with his new brilliant plan to defeat you. When you Wronski Feint him into breaking the tube of Conversion Gel, negating one of his advantages, he proceeds to explain how he tricked you into thinking that that was part of his plan, and then lampshades this trope by noting that he just made a mistake by telling you part of his plan. He proceeds to verbally backpedal several more times, tying himself in knots before finally giving up on the whole explanation business. There is also a subversion of the trope because his plan has a fifth part that he doesn't tell you.
The Heroic Spirits from Fate/stay night (except Berserker) are all responsible for doing this in one way or another and posture about their powers or how they know what the enemy's powers are (even Archer is guilty of this), but Gilgamesh really takes the cake. He freely explains his name, origins, his powers and his magic weapons to his enemies, simply because he is so ridiculouslyoverwhelminglyincomprehendably overpowered that it does not even matter whether or not people know his abilities.
Axe Cop attempts to kill Evilfatsozon using psydrozon◊ (a sword wielding robot). It fails, and Evilfatsozon explains he built psydrozon. Evilfatsozon begins to explain his weakness, "A uni—", but Axe Cop throws Uni-Man at Evilfatsozon, and defeats him before he can finish.
In an episode of Tempts Fate, the sub-comic of Goblins, a very ill-advised dwarf does this, explaining in detail the nature of his curse as he's introducing himself. It doesn't take long for Tempts Fate to exploit this weakness.
Dwarf: I have spent my life mastering combat using household items! For if I were to don a single piece of armour or grasp a single weapon, my god's personal avatar would personally descend from the heavens and destroy me! Just as it is stated in my terrible curse! Tempts Fate: Catch. (throw him a weapon)
On The Red Panda Adventures, one of the cardinal rules of crime fighting is: Never explain your powers to the bad guys!
Invoked and lampshaded in the episode Stop the Presses; when the Red Panda and his arch enemy The Mad Monkey, pushed into an Enemy Mine situation, discover that their respective mental powers can be combined for great effect, the hero begins monologing about the normal limits of his abilities. This prompts The Mad Monkey to ask, “Are you explaining your powers to the bad guy?”
Superheroes and (especially) supervillains in the Whateley Universe generally avoid this trope, with huge amounts of effort put into misinforming your enemies about your abilities - which makes those who do fall into this trap stand out even more:
UltraMax has done this several times now, each time when the Cadet Crusaders have run into Jadis Diabolik and her crew. Each time, the person he's blabbed to had used this new-found knowledge to gain an edge in the fight. He's apparently so bad for this, he has (or had) a website with a listing of his powers and how he uses them. He might start to get better about this, as of Jadis' last trip to New York with Jobe.
A stupider example happened when two supervillain wannabies explained their power sets to the whole town while asking for directions to the drug store (which they state they intend to rob). This allowed the weakest member of a visiting group of students from nearby Whateley Academy to take them out.
Cell explains his abilities to Corla in the DSBT InsaniT episode 'Beach Brawl', although she had already partially figured it out.
Tattletale, on the other hand, lies about how her abilities work to confuse and intimidate her enemies.
In contrast to the original manga, Rubber Soul tells Jotaro how his powers work in Vaguely Recalling JoJo because he's a narcissist.
The Ice King from Adventure Time should probably be more careful in fights.
Ice King: FOOL! Your powers are no match for my magical crown!
(Jake knocks off his crown)
Ice King: My powers!
In "Jake Vs. Me-Mow", Me-Mow boasts that she has injected Jake with enough poison to kill a dog fifty times his size. Which prompts Jake to use his powers to grow his liver fifty one times it's normal size, curing the poison.
Chaotic: Peyton plays it straight by explaining a key tactic mid battle and Eddy immediately uses it against him. He later subverts it, by explaining his own key tactics after the battle.
Gutierrez, from Freakazoid!, tries three items (kryptonite, the color yellow, and water) on the hero hoping each will be Freakazoid's weakness. None of them work, and when Gutierrez gets impatient and asks Freakazoid what his weakness is, prompting a cut to this:
For the record, Freakazoid's weakness is graphite bars charged with negative ions.
And "poo gas". Then again, no one likes "poo gas".
From time to time, the DCAU would get some of this to bring us up to speed on a character who is introduced without showing their origin. More and more as it went on, culminating in Justice League Unlimited.
In X-Men, after taking a few hits from Gambit's exploding cards, Bishop explains his mutant ability is to absorb energy from other mutants' attacks and transform it into energy bolts, which he then uses on Gambit.
Once per Episode in the little-known 1960s cartoon Batfink, he would tell his foes, "Your bullets can't harm me! My wings are like a shield of steel!"
In the "Menacing Family Affair" episode of the 1981 Shazam! animated series, an alien gives Dr. ThaddeusBodogSivana and his kids a jewel that gives them the same powers as Captain Marvel and the Marvel Family. While the heroes are reeling, Dr. Sivana brags about the "magic alien jewel", and from there the Marvels defeat the Sivanas in a few seconds by simply grabbing the jewel and throwing it away.
This is pretty much a recurring theme in The Perils of Penelope Pitstop. The Hooded Claw seems compelled (for some odd reason) to explain every little detail of each deathtrap to Penelope. This is probably the biggest reason they always fail; either the delay that the explanation causes or some information she gains from it helps her escape.