Laharl: What do you want? I’m busy right now. Mid-Boss: Tsk tsk tsk. You weren’t thinking of calling yourself the Overlord without first settling things with moi, were you? Laharl: I already settled things with you. Twice, as a matter of fact.
This even applies within the fourth wall. On several occasions they've helped Ash out or cheered him on in battle, because, as Meowth put it during Ash's battle with Tobias: "This is the guy who beats us all the time! So if he loses, think how bad it'll make US look!"
Subverted in the Best Wishes! series as Team Rocket truly Took a Level in Badass, even ignoring Ash and company sometimes. Officially zig zagged by XY, where they're back to their usual selves.
Lina Inverse from The Slayers actually gave this nickname to Naga at one point, as she constantly insists on calling Lina her partner (or rival, depending on which season/movie you're watching).
Martina from The Slayers NEXT is a very obvious example. Subverted in that she winds up with some Character Development and getting exactly what she wants at the end while Lina's still Walking the Earth, but then, she had stopped being a villain by that point.
Depending on the story, Zenigata can be this in Lupin III. No matter what the plot/enemy is, he's pretty much guaranteed to be involved in some capacity, but that can vary from him being a serious threat to Lupin and his plans, a grudging ally, a useful patsy, or (this trope) simply a minor annoyance who's only there because the fans would miss him if he didn't make an appearance.
Rex Raptor, Weevil Underwood, Mako Tsunami, and (to a lesser extent) Mai Valentine from the Yu-Gi-Oh! anime are basically this for the main characters or the bad guys. Although presented as credible threats, they pretty much exist for two purposes: another duel(against a supposedly strong opponent) to be won by Yugi/Joey, or to showcase how skilled a duelist a new character(sometimes the Big Bad) via The Worf Effect.
Less so in the manga, where Rex Raptor is never seen again after losing to Esper Roba, and Weevil is never seen again after losing to Joey. Mai also does pretty well for herself against Big Bad Yami Marik, even managing to acquire one of the God cards from him, only to find she couldn't use it. Marik really only won on a technicality—if Mai had been able to use the card, she would probably have won.
The MK5 from Beelzebub. It's even stated that losing in one page is their specialty.
Zonge and his followers in Toriko are a non-villainous version, though they are technically rivals to Toriko et al simply by virtue of being other Bishokuya, they show up in many arcs and are almost always ineffective (or if so, he is not deliberately effective).
In Rave Master there was the Jiggle Butt Gang (Big Butt Bandits in the dub) three crooks who were likely the most incompetent thieves in existence. How did they get their name? Guess.
The Jiggle Butt Gang is persistent enough to return even in a different series, specifically Hiro Mashima's second manga series, Fairy Tail.
The Wrecking Crew from The Mighty Thor were once a gang of super strong villains that could even give The Avengers a run for their money but in the past decade or so, they've become more of a punchline when superheroes need someone to beat up over and over again.
For example, to illustrate that the Juggernaut had gotten weaker after his Heel-Face Turn...he lost a fight with the Wrecking Crew. Losing to the guys who used to routinely give Thor a tough fight was treated as a pathetic embarrassment for Juggernaut.
Sin City has Shlubb and Klump, two idiot do-anything-for-a-job criminals that often show up and get pummeled by Dwight McCarthy.
Team Turmoil from Mark Waid's run on The Flash were this. Defeating was such a routine task that the Flash rarely bothered to interrupt his conversations while doing so - except to make fun of them, of course.
Korbal Broach and Bauchelain in the Malazan Book of the Fallen series are a rare literary example. They're actually brutal serial killers (Korbal is noteworthy for making golems out of the internal organs of orphans), which would lead one to think that the author might take them seriously. He doesn't.
Played with in Harry Potter. In perspective, Malfoy, Crabbe and Goyle pose less of a threat to Harry as Voldemort rises in power. Though the goldfish poop gang join with Voldemort, they come to realize that it's not as fun as it sounds. Ultimately subverted when the gang endangers the Power Trio's lives in the seventh book.
Subverted by Warren Mears, who goes from Goldfish to Piranha thanks to a wine bottle to the head & the luckiest gunshot in the world. Appropriately enough, he meets his supposed demise being flayed like a piece of salmon.
Harmony. After being turned into a vampire, she proved the most welcome of thorns in Buffy's side in large part due to her uselessness in a fight, culminating in the most epic push-fight ever.
Darien does have a personal grudge against Arnaud, as one of Arnaud's goons killed Darien's brother. Interestingly, Arnaud himself did not want Kevin Fawkes dead, as Kevin was a genius (and a friend) but forgot to tell his Mooks about it. Technically, though, the Mook was aiming for Darien, but Kevin pushed him out of the way.
Just remember this: Antagonists are probably the most common purveyors of conflict to appear in chronicles, and they can make or break a good plot. One common mistake is overusing antagonists or bringing them out from behind the curtain too soon in your chronicle. If, for example, you're going to have two or three major antagonists, don't let them tip their hands all at once. Keep some things secret. Likewise, don't make them too predictable. When you're describing the approaching Pentex First Team, the last thing you want is for the players to say, "Look, it's Delta Bob and his goon squad. Don't forget they're all carrying cans of pepper spray! Battery-powered fans at the ready, packmates!" You get the picture.
The last time you fight Solt & Peppor (which is optional), they actually do seem to get serious. Their Cross Slash attack can do enough damage to kill one of your party members, which you might not expect. They still aren't hard, but they're not a free win either.
Even earlier in Chrono Trigger, Ozzie, Flea, and Slash. Made even more apparent in a late-game sidequest during which you fight them again. For crying out loud, Ozzie gets taken out by a freaking cat. If that doesn't scream "unbelievable incompetence", then what does?
Gilgamesh in Final Fantasy V is the first one in the series, and one of the most popular ones too. He is once again a Goldfish Poop Gang member in Final Fantasy IX, going most of the game as Alleyway Jack before revealing his true identity. He also reappears as a Bonus Boss in Final Fantasy XII, makes a cameo in Final Fantasy VIII if the player has acquired Odin (who is killed by Seifer and replaced by Gilgamesh), and was retroactively added to Final Fantasy VI in the Advance series as a hidden esper. He is a Bonus Boss again in Final Fantasy Advance: Dawn of Souls. He is the only character in the series that is implied to have been the same person from game to game, in effect becoming goldfish poop for the whole series.
For Final Fantasy XII, It could be argued that Ba'Gamnan and his siblings fall under this trope, particularly later on in the narrative, but more or less it is averted almost all together. Likewise, much like other games set in Ivalice, the other villains never take up this role. Some have argued this is an intentional move by those who worked on that subfranchise to keep the tone serious. In Revenant Wings, however, Ba'Gamnan and his motley crew play this role perfectly. To the point that Ba'Gamnan's own siblings grow tired of his bumbling leadership and decided to ditch him, prompting the ruthless bangaa bounty hunter to beat some sense into them, literally, affer a kidnapping they staged went wrong.
The Elements from Xenogears. Of the four of them, their leader Dominia is the only credible threat posed to the party. Seraphita is so dumb she sometimes forgets she's a bad guy, Tolone spends much of her time reminding Seraphita she's a bad guy, and Kelvena just doesn't really seem to care all that much.
Dotty and Petty in Monster Rancher EVO most definitely fit this definition. You battle their weak monsters every so often, and they play this trope as straight as possible, often citing "Evil Villain Rules" that they live by.
Your rival in any of the Pokémon games, although in the original games he ends up becoming a credible threat again as the Final Boss. In the third, fourth, and first game of the fifth generations you have two rivals, the one that's the opposite gender of the player character and another one. (It's back to one in Black2/White2) The gendered rival in the third-generation games doesn't even fully evolve his/her starter and you never battle them again after about two-thirds of the way through the game. In X and Y you have four Rivals, but you battle three of them only twice apiece, the main Rival being more persistent. In most cases, the Rivals are often as much allies as they are opponents.
The anime version of the Team Rocket trio (see below) actually apply to this trope in the video game sense in Pokémon Yellow, despite being somewhat more competent in said game (like they were in the show before Villain Decay set in).
In somewhat of an example for Guitar Hero II (Xbox 360 version), Heart Shaped Box is significantly more difficult than the songs around it on Easy mode. It gets ridiculously easier on Medium and Hard, and stays mostly the same on Expert.
Liz and Ard from Wild ARMs 2, and the members of Cocytus, though to a lesser extent since they're all quite powerful and competent, not to mention that you fight none of them more than twice (Liz and Ard, however, are fought 3 times, almost always follow up a fight with them by throwing one of their robot bosses at you, and also accidentally set a VERY powerful optional boss on you late in the game).
And let's not forget the Schrodinger family (Maya in particular) in Wild ARMs 3. They pose a moderate threat (though nothing TOO bad), but they're still gimmicky comic relief and they reappear enough times to be annoying.
In Banjo-Tooie, Klungo gets three Boss Battles with our heroes. The first time, he's the Warmup Boss, and he doesn't get much more challenging after that, despite (randomly) switching strategies.
Banjo: Don't you ever learn? Klungo: Klungo clever, learn lotsss. Hasss learnt new potion. Kazooie: Is it as useless as all the others?
The Dark Wings from Tales of the Abyss are a fairly unique example. Unlike most examples, you don't actually fight them, and they're actually fairly competent. Not to mention that you're technically on their side once Asch hires them. That doesn't stop them from being comic relief that fill the storyline role to a tee, though.
Shogo: Mobile Armor Division features Samantha Sternberg, a hot-headed female who constantly appears out of nowhere, screaming that she'll kick the player's ass, only to be quickly dealt with with no trouble at all, yet somehow manages to survive every encounter. Near the end of the game, however, you have to face her on foot while she's in a Humongous Mecha.
Ace Combat 04's Yellow Squadron devolves into this in the final mission, since it had already been starting to take in rookies (with veteran members being transferred to augment other groups) even before the player shot down both Yellow Four and then their leader Yellow Thirteen; even though they're flying the same planes, for this mission instead of 150 points per Yellow shot down, you only get 90 points each.
Strigon Team in Ace Combat 6 go from being elusive, deadly opponents in the first mission to being completely wiped out multiple times over in later missions.
In Super Robot Wars D you had to fight five generals throughout the game and all five of their mechs in the final battle.
Adecor and Boccos AKA Tweedle-A and Tweedle-B, fulfil this role in Tales of Vesperia with their persistent bumbling attempts at arresting the protagonist. Though they are mostly dealt with in cutscenes, player involvement is only required when the game needs a punching bag for a Forced Tutorial.
That said, the final Tutorial fight with them, the Burst Arte tutorial, is annoyingly hard because it's two on one and they keep interrupting your attacks. Outside the storyline, you can also fight them in the arena (where they suck) and in the Bonus Dungeon (where they don't).
Wheeler from Pokémon Ranger: Shadows of Almia. While most of the members of Team Dim Sun, even the lower-level Mooks, like to throw down with relatively powerful (stolen and brainwashed) Pokemon like Rampardos and Magmortar, Wheeler is the sycophantic second-in-command to the Big Bad, and his Pokemon of choice is...Bidoof. And that's the only one he uses. Ever.
And in the sequel, Mana-Khemia 2: Fall of Alchemy, a set of different colored Punis that come after the party during Puniyo's character quests. They very quickly become annoying, because they have to be dealt with at least once per quest.
Subverted with the three Garlyle Forces female sergeants Nana, Saki and Mio in Grandia. You encounter and fight them repeatedly, but if anything they get more dangerous as the encounters go on, using a lot of new moves and fighting more as a team. They must have been leveling up and getting new kit just as busily as your party.
Then again, they attack you with paper fans, yo-yos, and balloons, so they're probably meant to be comic relief, even if the fight with all three of them together is That One Boss.
Phantasy Star Universe has the Vol Brothers, one of the most grievously irritating examples of this trope. See this review for a more detailed rundown of their effects on some players.
Big John from Viewtiful Joe 2. He constantly stalks the Joe and Sylvia across several movies with a different disguise each time. Two of the other bosses actually take him out themselves.
An even better example would be the Babylon Rogues from the Sonic Riders games, consisting of Jet, Wave, and Strom. They are never a threat to the heroes. They show up in nearly every race, though.
The BB Bandits in Fossil Fighters—or at the very least, the main Terrible Trio, consisting of leader Vivian, obnoxious lackey Snivels, and Team Pet Rex. When they first appear, they might seem tough, but quickly prove to be little more than a recurring nuisance. Even when you invade their base! However, after you beat the game and after their Heel-Face Turn, they're upgraded to Bonus Boss status—and a hardBonus Boss they are, too.
Sly in Mystic Ark. He's actually something of a threat when you first meet him in the second world, but then after beating the Beetle King, the guy starts to get a little strange. Then he just doesn't show up until the final world of the game where he expects you to give a flying hoot when he shouts "My plan is too brilliant for a dumbass like y-o-u to understand!" though he's surprising pathetic for a boss that late into the game, but then again, the game decides to subject you to two more moderately hard boss fights after him. He also never really did explain what that brilliant plan was...perhaps he's supposed to be Darkness' right-hand man?
In Breath of Fire III Ziggy is just a jerk you have to help a guy beat up to eventually gain access to a ship. But in Breath of Fire IV a similar Ziggy shows up who constantly challenges the party to fight him, and is not all that much of a threat what with low HP and, at his worst, can poison a member of your party.
Giacomo in Baten Kaitos Origins: Arrogant and headstrong, he goes from being a cruel Wake-Up Call Boss to one of these over the course of three fights. The last time he and Sagi fight, it's revealed The Empirethrew him out for being one of these, and Sagi even admits to envying his perseverance. However, by the time Baten Kaitosrollsaround, well...
Persona 3 has Strega, a team of Flawed Prototype Persona users that often hound the heroes. While they are responsible for killing Shinjiro, one of the more important moments of the game, aside from that they are for the most part mere inconveniences for the player who generally don't put up much of a fight (though it certainly helps that you always outnumber them).
Eat Lead: The Return of Matt Hazard has Sting Sniperscope, a meathead with a dumb accent. He's also Matt's (surprise) would-be replacement as video game protagonist and his intended executioner. With help from a hacker, Matt kills Sniperscope (effectively derailing his game's intended plot) and heads off on a quest to find out why the game developer wants rid of him. Matt has to fight Sniperscope two more times throughout the game, because he has three lives. Matt and Sting get more and more annoyed with each other every time they fight.
Penny Arcade Adventures: On the Rain-Slick Precipice of Darkness: Episode 4 introduces the Fish Force, a blatant Expy of Team Rocket, who even have their own theme song! They show up several times to menace the heroes, despite having no connection to the greater plot, and while they can be challenging to an underleveled party, represent no real threat. If you fight them enough times, at the end of the game they become your allies.
Shin Megami Tensei IV's Terminal Guardian is a one-man poop gang. Every terminal you find is guarded by one man, wearing a different disguise and throwing different demons at you each time you find a terminal.
THE Beastector in Mischief Makers, a trio of animal-men who have giant robots and goofy voices. They constantly hound Marina and bicker among themselves, and are actually challenging bosses, but in the grand scheme of the plot, they serve little purpose. They do end up as the final boss; after the real plot is over of course.
Star Trek Online: Ja'rod, son of Torg, captain of the IKS Kang, for the Starfleet player character. He tries to take them out several times during the "Klingon War" arc and ends up with Starfleet PC leaving the Kang dead in space every time. To add insult to injury, the PC then reveals Ja'rod's mentor Ambassador B'Vat was a nutcase trying to send the Klingons and Federation into a Forever War, and poor Ja'rod ends up on tribble extermination duty and the Kang gets disabled by the PC again.
Dondera Tank from Holy Umbrella for the Super Famicom is an unusual example in that your first encounter with him is a Hopeless Boss Fight. He still returns twice after being defeated, each time with a new tank and the same old bluster.
For a while in Sluggy Freelance, after Torg escaped from the Dimension of Pain demons, one of them would show up every Halloween to try and kill him and take his soul back to their dimension for eternal torment. The Main Charactersnever took these attempts seriously; they actually started charging people admission each Halloween to watch the demon try and kill Torg. However, during the "That Which Redeems" Story Arc, the demons get a major dose of Not So Harmless Villainyness.
Professor Lupin Madblood of Narbonic. Lupin tries to be the Big Bad, but ends up being easily defeated no matter what he tries. One time, he lost when a gerbil convinced his army of robots to unionize.
The ninja team from the Yama Dojo, in the Whateley Universe. Team Kimba thrash them before the team is really a team. They come back on Parents' Day (it's a Superhero School) and get pummeled so easily that Chaka has time to steal ninja weapons for some of the little brothers along with the visiting parents.
In Xiaolin Showdown, Jack Spicer starts out as an actual threat, but quickly undergoes Villain Decay that turns him into a one-man Goldfish Poop Gang, to the point where the Xiaolin Warriors start beating him up for sport and he's left with only a single Shen Gong Wu by the end of the series.
Scratch and Grounder themselves have Goldfish Poop in the form of Coconuts. They're all technically on the same side but rarely work together to capture Sonic, the former two being goal-oriented and the latter much more egotistic. Despite actually having half a brain over Scratch and Grounder, Coconuts is usually tasked with degrading housework (although he does tend to fail his solo capture attempts).
The Mutant leaders on Thundercats deteriorated into this over the course of the series, near the end unable to muster even a tiny iota of competence. At times, they even made mistakes they were even specifically warned against. (For instance, in one episode, Vultureman builds a thundrainium-powered cannon - thundrainium being a Weaksauce Weakness to Thundarians - but warns them that it won't work if fired at close range. This is exactly the miatake Sslith and Jackalman make when using it.) This is in stark contrast to Big Bad Mumm-Ra, who remained a major threat.
The Trix become this in the third season of Winx Club. While they were formidable foes in the first two seasons, they are horribly outclassed by the fairies' new Enchantix forms, to the point where any one of the fairies is often enough to take down all three witches.
Hack and Slash from ReBoot, who consistently fail to execute Megabyte's plans.
Bebop and Rocksteady from Teenage Mutant Ninja Turtles. Because regardless of species, common thugs/henchmen are no match for trained ninjas.
All the 1987 villains were delegated to this status during the Turtles Forever movie, mainly because they were stupid enough to release Ch'rell from his cosmic prison.
Sgt Blob, Frizz and Nug start off as this in The Dreamstone, blundering mooks for Zordrak, who constantly fall against the heroes in their attempts to steal their MacGuffin, and even described by the latter as "tiresome". Later seasons toy with this a little, since while still rather ineffectual, the heroes are actually degraded to be almost as bad. It helps they and Urpgor seem to be the only members of the villain army (the Big Bad himself included) that actually do anything.
The Amoeba Boys from The Powerpuff Girls. Their attempts at villainy are truly pathetic, although they manage to do something by accident that requires the girls' assistance to rectify.
Ben 10: the Circus Trio Freak, could be considered this, though they never really were a threat to begin with; most of the time, the only thing that makes them dangerous in the episode they show up in is the boss they are working for (successively Zombozo, Ghostfreak and Forever King Discroll). Most of the time, however, Ben kicks their ass pretty easily, to the point it's borderline humiliation for them.
The Shadow Hand in Jackie Chan Adventures. Doesn't help that their formerly badass boss got canonically retconned later on. The Shadowkhan at times as well, though their effectiveness appears to depend on how close the mask holder is.