Pokémon has a lot of Goddamned Bats, but most don't do much besides annoy you. Just when you thought it was safe to go into the water, you get attacked at every turn exactly like in caves, and there's a 90% chance that every single one of those is going to be a Demonic Jellyfish — Tentacool. Take Zubat's annoying Supersonic, making your Pokemon hit itself, but add on that it has multiple attacks which can poison your Pokemon as well; and unlike most of the Standard Status Effects in the game, confusion and another effect can be on a Pokemon at the same time.
It also doesn't help that the Wrap attack that annoyed you in Gen I (see below) had been downplayed in exchange for also preventing Pokémon from escaping thus giving Tentacool and Tentacruel equal potential for annoyance.
Also, you can cure confusion by spending a turn to switch out your active Pokémon. Wrap prevents you from switching out your active Pokémon. Cue the rage.
Thankfully, their Unova expies, Frillish and Jellicent, aren't as bad- they still show up constantly, are immune to Normal and Fighting, and have the capabilities to disable your moves when you damage them- but at least they're slow.
Generally speaking, the later the generation of games, the more likely a particular Pokémon would become this. Newly-introduced Pokémon will have previously unseen dual-typings and movepools. And Pokémon from previous generations will also have new moves and abilities introduced to improve the Pokémon's competitiveness, as well as existing ones being Ret Conned. Such things generally results in more possibilities of how your Pokemon can get screwed over.
Hypno from Pokémon FireRed and LeafGreen definitely counts. You'll first encounter one in the 5th Gym who is at level 38, which is very likely higher than everything you have on your team if you fight Koga before Sabrina. Killing this thing is a nightmare with a decent 85 base HP, 73 base defense, and a whopping 115 special defense. Not to mention it's one of the few Pokemon that Alakazam actually CAN'T do significant damage to. You can skip this particular trainer, but if you're playing this for the first time or like to fight every trainer you have to ride out the storm.
In the Gen I, any Pokémon with Wrap, Fire Spin, or Bind that had a higher Speed stat than your Pokémon qualified as one of these. It would Wrap you once, then continue to Wrap you every turn (during which time you were COMPLETELY incapable of moving) thereafter until the effect wore off. Then it would Wrap you again before you could counterattack, unless you used Quick Attack.
In Gen I, Growlithe is this if you're trying to catch it. It's a good choice of Fire-type for your team if you didn't pick Charmander, but it can use Roar to scare your Pokemon away whenever it feels like it, which is really annoying when all you're trying to do is whittle down its HP to a low amount. Your best bet is to put it to sleep as soon as possible to avoid this risk.
Abra is even worse. You want the grossly overpowered Alakazam for your team, but actually catching the Abra is tricky because all it knows is Teleport. If you don't put it to sleep right away, it will run away from you. Then once you catch it, it can't really battle on its own until it evolves into Kadabra, which makes things even harder.
Pokémon Stadium pretty much had a really, really annoying variant of Wrap and high Speed stats in the Elite Four battles. The last member sent out Dragonair, which used Thunder Wave to paralyze the Pokémon, and then Wrap for the usual effect. Made worse by how Thunder Wave by nature basically halves the speed stat of the target Pokémon, meaning the opponent nearly always attacked first and got to use Wrap near constantly.
Graveler are tough, but have enough weaknesses to make them mere Goddamned Bats — however, if you let them do anything at all, chances are they will not waste a single turn before exploding, likely taking one of your six Pokémon with them. Only to be replaced by a new Graveler after a few steps. Rinse; repeat; run out of Revives. Also note that fainted Pokemon do not gain any EXP.
It got worse in Gen. V. Before then, the Sturdy ability that they have only protects them from One-Hit Kill moves, such as Horn Drill and Fissure. In Gen. V, Sturdy also allows that pokemon to survive any attack that would KO them from full HP, bringing them to 1 HP instead. In Graveler's case, that means it doesn't matter if you go first; it still survives and if it decides to Self Destruct...
Weezing are worse than Graveler: they are tanks, they lack a convenient 4x weakness, and they are immune to Ground, which leaves you one option: Switch in a Psychic. Psychics rarely have huge defense, so they WILL die if those guys explode. The only good way to deal with them really is to send in a Steel and tap them with non-super effective moves, send in a Ghost type and watch your opponent explode in a smoldering cloud of FAIL, or have 'mon with the Damp ability as your lead. (Damp nullifies Explode and Self-Destruct).
In Pokemon Mystery Dungeon Explorers of Time/Darkness , there's... most anyone with Silver Wind or Ominous Wind. These moves can hit ANYWHERE in a room (if you and the opponent are in a room. Otherwise, it's anyone two spaces away) and if they hit, there's a chance it raises the user's Speed (as well as other stats). Which then allows them to DO IT AGAIN. And there's more chance of it happening for extra member in your party. And if you can't attack from a distance or they aren't in range, they may use it again. But the worst one? Drifblim. In addition to being a tank, its first ability allows it to attack twice in one turn, meaning it has TWO chances to raise its stats, multiplied by the amount of targets it hits. And it has a chance to blow up on you (though you only take damage if you defeat it up close.
Thanks to Unburden and Aftermath, Drifblim are also capable of exploding three times in a single turn if the A.I. Roulette happened to select "Explosion".
Rotom can use Ominous Wind while INSIDE WALLS. And the only way to hit someone inside a wall is either with specific-ranged moves or direct contact moves with an extremely rare mobile scarf (assuming they're in range).
Any Pokémon that can use a move that can hit anyone in a room can be such if they use it enough. And then there's the move Agility (and the lesser-used Tailwind), which raises the user's Speed... and all of its allies in the same room. And if you ever run into a monster house with Agility-users and they get a chance to do so, expect to be attacked at least five to ten times in one turn.
While on the subject of agility, Porygon and its evolutions combine that and the room-hitting Discharge (which can paralyze you, putting you at half Speed and letting them ATTACK AGAIN).
Porygon-Z used Agility! Porygon-Z's Speed increased! Porygon-Z's Speed increased! Salamence's Speed increased! Porygon-Z used Agility! Porygon-Z's Speed increased! Porygon-Z's Speed increased! Salamence's Speed increased! They all attacked you 10 times before you could move! It's super effective!
Dusclops has the move Curse the first time you encounter them.
Explorers Of Sky has the Gulpin in the lower levels of the Star Cave in Special Episode 1: Bidoof's Wish. They can use Poison Gas to poison you, but they tend to use Yawn to put you to sleep and then wail away at you. Since you're playing a Normal-type with around 50 HP in this episode, it tends to be an incredibly annoying and often deadly encounter, and they won't go down without a fight either.
As a Steel/Psychic hybrid, Bronzong only has two effective weaknesses prior to Gen VI, and at least one of those weaknesses will always be negated if it has the Heatproof or Levitate ability. A Pokémon with Mold Breaker bypasses these abilities and hits for super-effective damage regardless. Reshiram's Turboblaze ability also allows it to bypass one of the abilities and incinerate Bronzong— sadly, this is an uber we're talking about. At least a ton of other Mold Breakers have also been added, most noticeably Haxorus (Druddigon's speed stat is trollishly low, as is Excadrill without its speed-in-Sandstorm ability; Basculin has a terrible movepool, Pinsir and Rampardos are rarely used, Throh is amazingly slow, and though Sawk has decent speed, it still gets outrun by most OU sweepers), so this is somewhat less troubling.
Thankfully in Generation VI, Bronzong has been nerfed with the changes to the type chart, meaning that Ghost and Dark are now super effective against them! No more playing the "Levitate or Heatproof" Guessing Game.
Generation III has Dewford Cave and their Sableye. No weaknesses and half-decent stats. Plus, seeing as this was the first ever Ghost/Dark Pokemon ever, many players would have wasted time trying to figure out its weaknesses. Luckily for Ruby players, only Sapphire and Emerald had them.
Meet Plusle and Minun. Unless your starter was the only Pokemon you raised up to this point, you won't be knocking out either of these with one hit. After it continues to stare you down with its "cute" face it will then proceed to use Thunder Wave and paralyze your Pokemon. Traveling through Route 110 without a Poké Mart's worth of Parlyz Heals is a stupid thing to do.
The "no weakness" category took on two new members in the form of Gen IV's Spiritomb, also a Ghost/Dark type with simply annoying moves like Pain Split, and Gen V's Eelektross, an Electric type with great stats and Levitate. Ground moves don't hit it, people! The former serves as a mixed tank and the latter a mixed sweeper in competitive play; they are not nearly common enough in standard battles. Sableye and Spiritomb finally received a weakness in Gen VI in the form of the new Fairy type.
Jirachi, in competitive battles. Thanks to a combination of Iron Head with its Serene Grace (doubles likelihood of added effects on moves that have them), the little devil gets an 80 power STABed move with a 60% chance of flinching.
Even worse is Togekiss. Take that same 60% flinching STABed attack (backed with a base special attack stat of 120), throw in a Thunder Wave and you've got an enemy that allows you to attack only 30% of the time. And it can heal itself. And it has access to multiple moves (Ominous Wind, AncientPower, and Silver Wind) that deal damage with a 20% chance of boosting all its stats, aka "I win."
There's also the infamous Swagger Prankster set; Liepard is easily the most notorious for it, though Murkrow and Purrloin can duplicate it and Sableye can run a variant of it. First, take the ability Prankster, which all but guarantees any non-attacking move goes first, and combine it with Swagger, a move that doubles your Attack but at the same time confuses you, which gives you a 50% chance of attacking yourself - and with that doubled Attack. Then add Substitute, which gives Liepard a shield it can use in case you do manage to get an attack off. Next, add Thunder Wave, which gives you a 25% chance of skipping your turn entirely, on top of the aforementioned confusion, and also cuts your Speed to 1/4 to add insult to injury. Once you're at Liepard's mercy from all the status spam, it'll finish you off with Foul Play, a move whose base power runs off your Attack stat instead of Liepard's - and did you forget it doubled your Attack earlier? And then you send in your next Pokemon, only to find Liepard has its Substitute shield readied, meaning the new mon will find it even harder to break through than your first one. While it's far from the most reliable set, and can be hilarious when it backfires, nothing is more infuriating than seeing your entire team wiped out with this sort of status spam.
Another annoying set (that also involves Prankster) is the Assist + Shadow/Phantom Force set. By using Assist to pick Shadow/Phantom Force from an ally, Liepard can become immune to all attacks for that turn. On the next turn, Shadow/Phantom Force hits even when Protect is used. However, the Liepard also carries a Lagging Tail, which causes it to move last. The result? Nothing can set up on it, defend, or try to outgun it, as it's going to always hit last but be initiated before anything else. The only way to stop this is to send in a Normal-type or try to take it out with a faster priority attack (which, since Liepard is so fast, is difficult to do).
It should be noted that Explosion and Self Destruct were heavily nerfed in Gen V. In previous generations, they halved the targets' defense, but this no longer occurs. It still hits hard, but it is no longer a near-guarnateed OHKO.
While not a traditional Pokemon Demonic Spider in that it very rarely appears in the wild, Emolga is very nasty in the hands of most of the Mooks using it. You spend hours biking back and forth in search of Audino. When you finally see the shaking tall grass, you walk right into it, expecting a friendy Audino, then BAM, Emolga shows up. Normally you'd use a Ground-type to deal with Electric-types...except that Emolga is part Flying, making it immune to Ground attacks, and you first encounter them in the Nimbasa Gym - where the leader has two of them. They're only weak to Ice and Rock - at that point, Ice is nonexistent, and Rock is only available in the form of the fossil Pokemon (which require backtracking, are weak to Electric, and are slower than Emolga), the aforementioned Boldore (who is very slow and not immune to Electric, unlike Graveler), and the TM for Rock Tomb, which you just may have missed in that huge desert (and it's a pretty weak attack to begin with). Later users of Emolga up the ante by teaching it Double Team, making them nigh-impossible to hit. Plus, hitting them with a physical contact attack has a chance of your 'Mon getting paralyzed. Thankfully, a Drilbur (high attack, naturally learns Rock Slide at 29, immune to Electric) can take them down if it manages to hit with Rock Slide.
Just to cap off the pain, defeating Elesa's team of Emolga opens up access to Cold Storage, which is teeming with Vanillite, a Mon that seems tailor-made to fight off Emolga.
Emolga is back and just as annoying. In Kalos Route 10, you can find them along with resident spiders Sigilyph and Hawlucha. This time, Emolga has a new method of torture: Nuzzle. While it does not do a whole lot of damage, the secondary effect just happens to have a 100% paralysis rate. That means this flying squirrel is going to cripple your mons and make it harder to run away from and it also is packing other nasty moves to hit you a fair bit.
If you've been wandering around the Desert Resort or Kalos Route 10 for too long, you can run into a Sigilyph: Hard to run away from, stats comparable to fully-evolved Pokémon, and it packs Whirlwind, which it can use to flee in order to avoid letting you get your powerful ally. Bosses and even mooks with Sigilyph are usually really painful to deal with.
Watchog. That thing is unfair. First, it has Hypnosis. It has shaky accuracy (70 when the max is 100), but if it hits, you are instantly put to sleep and unable to attack. If you use a sleep-ridding item, next turn it's going to sleep you again. While you're asleep it uses Confuse Ray to ensure you have trouble with anything when you wake up. It also has Detect, which protects it for one turn against ANYTHING. Meaning it's potentially enough for your Pokémon to hit itself in confusion. And to note, Watchog evolves early, so you'll find it a lot, AND it's probably faster than ANYTHING you have at that point. It also has Super Fang, which halves your current health. It's also capable of hurting you regularly with Crunch. If you encounter one, be wary. Very wary.
And the game wants you to know it as well. Lenora is the second Gym Leader, and her Watchog is the second Pokemon in her lineup. If what was mentioned above wasn't nasty enough, it also knows Retaliate, a 70 power move which doubles in power if an ally was knocked out the previous round. It always starts with this move, so bring a tank like Roggenrola or have a decoy Patrat use Detect to annul the damage. After that, good luck— you'll need it!
Thankfully, you have access to Fighting-types like Sawk by this point.
Although if you want to cheat right back you could catch one with Hustle and teach it Hone Claws boosts attack and accuracy) by TM... or search for the rare ones that don't have Hustle. Too bad that you can only find the Hone Claws TM post-Elite Four; in other words, when there is no necessity to solely use Unova Pokemon.
One strategy in the metagame is to use Durant's Entrainment to keep the other pokemon from attacking every other turn and switch to Dugtrio where it will proceed to Hone Claws/Protect its way to maximum attack and proceed to sweep. If you're not prepared for this, you'll be in trouble real quick.
If you think you could get away with a Fire-type, some of them know the move Dig, and they will use it. You can still change to a Flying-type or Levitating Pokémon, but this alone can make the battle last nearly forever, especiaally if they have high speed. Especially annoying when you try to level grind before facing the Elite 4, as some of them can pull off this trick even when your level is 25 higher than theirs.
Notably though, you can catch these pretty easily, and turn them (and their evolutions, who are arguably both much stronger and rarer in the wild) against your foes..
Audino becomes this early on. While they're useful for Level Grinding, they're absolutely annoying otherwise (Looking for that one rare Pokémon that can only be found in the rustling grass? Nope, have an Audino instead). Audino has surprisingly high base stats compared to most unevolved Pokémon; it also carries an Oran or Sitrus Berry most of the time, and it takes forever just to get it down to half its HP due to its high Defense stat. Around level 20, they learn Attract, which immobilizes 'mons of the other gender; and Secret Power, which puts your 'mons to sleep (thanks to their location) so often, you almost expect for it to happen. Fortunately, they become less of a threat later on.
Oh, Zebstrika. It's annoying enough it's a relatively common annoying Pokemon in the mid-game, but its moveset is what makes it such a pain for players to battle. Its high speed status is bad enough. But, it just loves to spam two moves in the wild. The first is Spark, an Electric-Type move that has a chance of paralyzing the player's Pokemon. The other move? Flame Charge. A Fire-Type move that is not only super-effective against Grass-Type Pokemon (Thought your Serperior would have the advantage being resistant to Electric-Type attacks, huh?) but also increases Zebstrika's high speed stats. Brought a Ground-Type to fight it? It can just use Stomp to pound your Pokemon into submission. It also has a really, really loud cry.
What makes Blitzle/Zebstrika even more annoying is that it's absymal defense (and the EXP scaling) makes it utterly difficult in raising it. Normally, most Pokemon would be able to take hits when it's properly levelled. Not this Pokemon; a critical hit from even wild Pokemon several levels lower will OHKO Zebstika, and this can include Flying-type moves, which Electric-type Pokemon should resist. And you can forget about OHKO-ing the other Pokemon, because Blitzle/Zebstrika's attack stats are actually mediocre at best. And until you earn the fifth badge, Zebstrika and Emolga are the only Electric types you can find. A case where whether Zebstrika is with you, or against you, you're pretty much bummed.
Whimsicott. Not only are they fast as hell, they can also have the Ability Prankster, which increase priority of non-damaging moves, essentially guaranteeing that status moves go first. A Whimsicott equipped with powerful status moves and Prankster essentially cannot be outsped whatsoever (unless under the effect of Taunt; but that can be cured by switching and it's a rather uncommon move). They can use Cotton Guard to boost their Defense at such a horrifying rate that after a mere two turns of use, they have a 400% Defense boost; or just spam Cotton Spore, which will send you to minimum (aka one-quarter) speed after three turns of use. If that's not all, they also have access to Hurricane- an attack which, if it doesn't outright one-shot you, can confuse you. Try to put up Light Screen to dampen Hurricane's damage? It may have Infiltrator instead, which ignores it. Intense sunlight in place? If they have Chlorophyll (only possible in regular player matches), nothing can outspeed it outside of increased-priority moves, and it knows Tailwind to up the speed of any remaining team members, which they'll very much use when about to go down. At least they're fragile.
Mienshao. Fast as hell, packs a punch, and it naturally learns Fake Out, Drain Punch, and U-Turn (which lets it switch out from any threat not faster than it). Trying to use Fake Out on it may not even work, as it has Inner Focus. It can also heal itself whenever it switches out. It's got pathetic defenses, but it's fast and strong enough to wipe out your entire team if it gets the chance.
Lilligant in Pokemon Mystery Dungeon: Gates to Infinity are absolutely ferocious. If you run into one, she'll use Teeter Dance to confuse the entire room while other Lilligant have a good chance of being immune to it. Then she'll use Quiver Dance to double her speed and boost both Special stats, and then pummel you with Mega/Giga Drain, which takes huge chunks out of your health and drain it back while you're helpless. Running into a Lilligant while alone is a death sentence. Running into two or more is certain death unless you can strike first.
Their pre-evolved form Petilil isn't much better, because she knows Sleep Powder, which has a fairly high accuracy (for the AI, at least) and puts you to sleep, and can be used around corners. At that point, she will spam Growth and Mega Drain to draw huge chunks out of your health and heal it back, while completely helpless. If your character is Oshawott, you're definitely in trouble.
Deino, for two reasons: Dragon Rage and evolution mechanics. Dragon Rage will most likely one- or two-shot an ally, and if that happens, Deino will evolve into Zweilous. In this game, when an enemy Pokémon evolves from defeating an ally, its level is boosted to the level that the Pokémon normally evolves at. What level does Deino evolve at? 50. Your attacks won't be able to harm it, and even its weak attacks will demolish you several times over... at which it'll evolve into Hydreigon, which evolves at level 62. You're dead when that happens unless you can use an Orb that petrifies it or puts it somewhere else. When Deino no longer learns Dragon Rage, you're safe. Until that happens, or if you're in the Slumbering Cave? Good luck.
The final forms of the elemental monkeys (Simisage, Simisear, and Simipour) are all very fast and can dish out huge amounts of damage with ease. On top of that they have large movepools, meaning that there's not much that's safe from them. They take hits like glass but that doesn't really help when one of them plows through your entire team... or worse, two of them at the same time.
In the Battle Subway they are infinitely more aggravating to fight. Most of the time they'll use Focus Blast, a very powerful but inaccurate attack that'll probably one-shot anybody that's weak to Fighting. Plus, they're so ridiculously fast that you'd swear they have Choice Scarfs (which lock them into one move, but give them a 50% speed boost), but analysis reveals that they don't. They're just that fast. Given that they only appear at the last few matches, it makes losing to them far more excruciating.
For those who activated Memory Link and talked the Pokemon Breeder in the Center, you have the possibility of encountering a Darmanitan in Desert Resort. It's level 35, which is very likely to outlevel anyone in your team by 10-15 levels. Furthermore, all of N's Pokemon have IVs of 30 in each stat, including this behemoth, so it's going to outspeed almost anyone on your team and one-shot them with moves like Thrash and Flare Blitz. note Thankfully, because of its nature (all of N's Pokémon have pre-determined natures), its attack stats are actually lower than usual. But here, that doesn't really matter. Your only hopes of escaping are either to catch it with Great Balls at best, or hope it uses Hammer Arm so its speed drops. And if you do the latter, you may encounter it again. Have fun.
Gliscor in competitive play. What's more annoying than a Stone Wall with only two weaknesses, two immunities, incredibly high Defense, and a great offensive typing? One that can heal itself when poisoned. This means you can't cripple it or wear away at it with other status effects unless you get rid of its ability. In addition, the most common sets consist of spamming a combination of Protect, Substitute, and Toxic, an incredibly frustrating strategy. Unless it can be one-shotted (which won't usually happen), agony will ensue.
ANY Pokemon in a Horde Battle that uses a Stat-Lowering attack, especially Sand Attack and Leer from Scraggy in Route 5. They're spam it on you and then use a weaker attack to slowly take you out.
If you get unlucky, you'll run into a particularly infamous Pokemon in Reflecting Cave - Wobbuffet. That Wobbuffet. You can't run, you can't swap out, all you can do is pray your lead Pokemon has a type advantage over them, or some other way to incapacitate them quickly. If you don't, not only do you have to deal with their counterattacks, but also their frighteningly smart AI; they'll put up Safeguard to block status ailments, and use Destiny Bond when they get low on health.
This also applies to when wild Wobbuffet appear in Cerulean Cave in the third and fourth generations.
Hawlucha show up on Kalos Route 10. They're incredibly fast, making it hard to escape them. While you're trying to run, they'll be smacking your team around with STAB Aerial Ace. And if you try to take them out, it turns out they know Roost. Depending on their level, they'll also either know Karate Chop (thought your new Fossil Pokemon would help here? WRONG) or Encore.
That route's also full of Sigilyph. Sigilyph are also really fast, and they know Tailwind to up the speed even more. Their type combination is really hard to counter (Psychic/Flying), and they know Psybeam and Air Cutter, which hit decently hard and have a chance of causing confusion or boosted criticals, respectively. Just to add insult to injury, they also know Whirlwind, and love to blow you out of battle before you can get a Ball thrown. On the bright side, you can catch one and use it against Hawlucha.
Kalos Route 11 has a pair of nasty Pokemon who just love to screw you over when you least expect it.
Sawk (X only) is just plain brutal with Fighting attacks and Counter, and the Attack and HP to back it up. If you don't have something resistant to Fighting, you're going to have to make a swap or two to keep your Pokemon from getting plastered. Throh is probably just as bad.
Hariyama is even worse; its HP means it just won't drop, its HP means it can eat Psybeam with a smile, its Attack is insane, and as one last screw you, it can eject you with Whirlwind whenever it feels like it, assuming if you're using a lower-levelled Pokémon against it. "Put it to sleep, then go for the throat" is the only advice we can give you.
Route 12 is full of Miltank. But you just got a level 32 Lucario handed to you, they shouldn't be too much of a problem, right? Well, they're tough enough to tank Lucario's super-effective moves for a turn or two - just long enough to get off a Bide, which will almost certainly take down Lucario. They also know Milk Drink, so they can heal pretty much at will, as well as Rollout and Body Slam. Did we mention they can almost certainly outspeed almost anything you can throw at them?
Route 12 also has Chatot. If you can't knock them out or otherwise incapacitate them on the first turn, then they will hit you with Chatter, which not only runs off Chatot's respectable Special Attack and gets STAB, but is also guaranteed to confuse whatever it hits. If they don't Chatter you, then they'll probably put you to sleep with Sing and then Chatter you to death.
Torkoal in X/Y. This shouldn't be too hard. Just use a Water-Type Pokemon and squirt it.. Wait, is it spamming Iron Defense? Not too frustrating. Use a special attack against it....And it's spamming Protect now. Now it's getting frustrating. Well, at least it's just defending itself and....Did it just KO my Pokemon with Lave Plume!?
Furfrou. This poodle Pokemon will quickly become one of the most annoying mons to battle early in X/Y. Why? Because it loves to spam three moves. Those moves are Growl, Baby-Doll Eyes, and Sand Attack. Both Growl and Baby-Doll Eyes will lower your Pokemon's attack, and Sand Attack lowers their accuracy. In other words, you'll be spending a good portion of the battle either barely doing any damage at all, or being unable to hit the bloody thing. The only way to beat it is if you're lucky and fast enough to strike it with a super-effective move. And even then, their "Fur Coat" ability reduces the damage taken from physical-damage moves, which nearly all Fighting-type attacks are.
Pachirisu in X/Y is a huge annoyance. Pretty much every battle against it will boil down to "Pachirisu used Nuzzle!" "X is paralyzed!" "Pachirisu used Endure!" "X used (Insert attack here)!" "Pachirisu endured the hit!" "X is Paralyzed! It can't move!".