These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ceadeus, to most. While its attacks are fairly damaging and difficult to dodge if you're close to it, especially without the Lagiacrus armor, you can't fail against it unless you faint three times or don't cut its beard before it gets to Area 3. Upon hitting the seemingly narrow time limit of 30 minutes, it flees and you get some materials. You are then free to take the quest over and over until you've completely whittled down its health. 3 Ultimate lampshades this by demoting Ceadeus from a 6-star monster to a 5-star monster, putting it on par with more common, albeit powerful monsters. Goldbeard Ceadus, on the other hand, is a different story; see That One Boss below.
The two kings of this trope are probably Lao Shan Lung and Yamatsukami, both of whom are even more predictable than the above. Lao doesn't even have a move that targets players on the ground, whilst virtually every one of Yama's attacks is clearly telegraphed and easily avoidable even if you have the reaction time of a dead cow.
The Ivory Lagiacrus in Tri Ultimate is hyped up pretty heavily in game, being the monster that eventually forced the Village Chief into retirement from his hunting career and all, and is also the last fight before the credits sequence. In practice, however, it's a slightly stronger Lagiacrus who has roughly the same (or, in some occasions, less) health as most of the fights leading up to it, fights nearly entirely on land (generally considered to be easier than fighting them in water), and whose only real additional threats compared to the normal Lagaicrus are slightly wider hitboxes on its electric attacks and slightly increased damage.
Barring monsters with dodgy hitboxes or unstable animations, any fight can be mastered due to each beast's well defined behavior. Unfortunately even in offline mode most players will have to run them until they become easy if they want to craft good equipment.
Awesome but Impractical: Some monster attacks. An example that springs to mind is Agnaktor'sMagma Beam. It's an incredibly powerful attack that can inflict severe burns and has a great aesthetic coming off of one of the most metal monsters going, but unless it actually bothers to spin around, anyone with half an idea of what they're doing (which by the point where Agnaktor is encountered, you should) will find it so easy to avoid that it's essentially a few free hits.
Complacent Gaming Syndrome: One of the series' trademarks used to be the rock-paper-scissors mechanic of picking a weapon with the right elemental type to be good against your enemy, then Monster Hunter 3 Ultimate added the explosive slime element. Slime does massive damage and isn't actually resisted by anything, so many players just make a good slime weapon and then never use anything else ever.
Cult Classic: A strange example because even though in Japan these games are easily considered a Killer App and very popular, internationally, it is much less popular overall but the fandom of it still very much love the games. This is one of the main reasons that half of the games are not released outside Japan.
8.8: Yahtzee's review of Tri sparked an edit war on the ZP Dethroning Moment page and a Hiroshima's worth of backdraft across the internet. Things got worse when he talked about the game in his "Extra Punctuation" column the following week, in which he announced that he had stopped after the Great Jaggi fight. Said fight is occasionally considered by the community to be the unofficial end of the tutorial for Tri, which certainly did not reflect well on him in their eyes.
Hammers in Tri: attack twice then windup charge, then attack immediately after you go into charge mode, and repeat. You'll attack as quickly as with a Sword & Shield.
The Slime element introduced in Monster Hunter 3 Ultimate, which throws the balance of the game out the window, making the other elements obsolete. The Kelbi Bow, with the Awaken skill which unlocks its Slime element, is becoming infamous because of this, thanks to its level 1 charge spreadshot (5 shots), allowing it to inflict the Slime element quickly and easily For Massive Damage. And that's before you apply bonuses from Bomber skill. Granted, monsters will gradually increase their resistance against Slime elements (like any other status attacks), farming Brachydios is not easy, and slow weapons prefer high raw damage to status or elemental attributes, but Slime's utility makes it a great all-rounder.
The Battle Tonfas introduced in Frontier are criticized for being this due to their highly versatile moveset ruining the competitive balance. It has the mobility and versatility of Sword & Shield, the attack speed of Dual Blades and charge gauge-based special attacks like the Charge Axe, but with spontaneous damage output like the Gunlance's Wyvern Fire and the ability to do jump attacks similar to the Insect Glaive, with the added perk of being able to jump kick against the target to remain airborne for an extended period, leading to Tonfa players pulling off DMC-style air combos that also serve to help dodge ground-based monster attacks. On top of that, it can also switch between both Impact and Piercing damage at will using the charge gauge and is therefore the quickest impact weapon you can use to knock out a monster. Japanese fans have claimed that this weapon has at once put Lance, Hammer, Dual Blades and Insect Glaive all to tears. Observe.
Goddamn Bats: Quite a few of them. "STUPID VESPOIDS!" and "STUPID BULLFANGOS!" is practically a catch phrase to some hunters.
Tri adds Goddamned Rhenoplos to the mix. Basically they're a mashup of a Bullfango and an Apceros - they share the Bullfango's love for charging but knock you even further, and they have health about equivalent to an Apceros. Add in armored craniums that can deflect frontal attacks of even green sharpness and you've got one annoying enemy.
Tri also adds Bnahabras, souped up Vespoids. While Vespoids were annoying for sneaking up on you then leaving you vulnerable to attack by a paralyzing sting, Bnahabras add in the ability to shoot a defense-lowering goop at your hunter, making everything else hurt more.
The Melynxes in Tri don't hurt you, but they steal your items. What they steal could be anything from an Insect Husk to a Max Potion. Granted, you can get them back by hitting them or going to the cat statue if they flee, but you don't want your more valuable items getting swiped while you're fighting something else. Fortunately, they can be distracted if you use a Felvine Bomb on another monster.
In Tri Ultimate, all of the smaller minion bird wyverns. Male Jaggi are tolerable and rarely knock you down. The larger female Jaggia however have a full body check that sends you flying as far as a Bullfango/Rhenoplos charge plus a bite attack that knocks you down. Wroggis also have the same body check as the Jaggia and a poison breath attack. Luckily its not as potent as a fully grown Great Wroggi but the thing that sucks is Great Wroggi will target you with its strongest attacks when you are poisoned. Baggis are just as annoying with their sleep toxin that'll drop you in about 10-15 seconds. Like Great Wroggi, Great Baggi will hound you as soon as you get drowsy. And they sometimes attack your prey when its sleeping.
Before Tri and in 4, there is the Gypceros, a monster encountered fairly early in the game. While it doesn't have much damage potential, it has an annoyingly tough hide for that point of the game, spits poison projectiles, has a flash bomb-like attack that can stun you, can charge in multiple directions without stumbling while spitting poison bombs left and right, and even steal random items that cannot be recovered unlike with Melynxes. It also has a move where it will play dead and attack if you come near, but at least you can carve some materials from it during that move if you're quick enough, and it also serves as an indication that the Gypceros' health is getting lower.
The Baleful Gigginox. It ditches its egg-laying ability, freeing you of the worry of Giggis leeching your health away, but in addition to some powerful thunder attacks, it also has a tendency to roar. A lot. And basic Earplugs won't protect you; you need high-grade Earplugs to shield against its roars.
Hell Is That Noise: Some wyverns can produce utterly otherworldly roars, take Diablos, Khezu or Gigginox, for example.
A few hunting horns are capable of this, too; in particular, the Apocalypso, which lets out a loud shriek when a song is played on it; and if you're playing with someone using it, you'll be hearing that sound A LOT. Thankfully, unlike most examples of this trope, the sound is a good thing, as it means that you and your teammates in the room will be receiving a status buff.
Uragaan, before certain attacks, makes a kind of odd noise that sounds like a deep wheezing noise, typically during its chin slam but other attacks as well. This is usually the sound you hear before you enter a whole world of hurt.
Hearing the Deviljho's roar is bad enough considering what's coming your way, but the roar itself sounds less like it comes from a creature and more like a bomb going off.
Internet Backdraft: When news that Monster Hunter Tri was going to be a Wii-exclusive, the 360 and PS3 fans did not take it well.
When fans found out that not only is the Updated Re-release of Tri exclusive to the Nintendo 3DS, but the upcoming sequel as well, fans weren't amused.
In a less Console Wars-based example, the fact that the 3DS version of Monster Hunter 3 Ultimate has no online multiplayer, being limited to local multiplayer, made some people bitter, especially considering that Monster Hunter 4, which will be released on the 3DS too, will offer online multiplayer. The Wii U version of the game will allow online multiplayer, though.
Les Yay: The female owner of the item shop in Tri REALLY likes hunters, even if you choose to play as a female. At one point she will even crack a joke about accepting a lock of your hair for an expensive item.
The sound that plays when your character is stunned.
The meowing of Melynxes when you're trying to fight another monster.
Fittingly enough, the monsters' roars, especially if employed in succession, as they render you immobile for the length of the roar and, in rare cases, damage you. Monster roars can get very old very fast.
The Scare Chord that plays when you get knocked out, especially if you keep getting beaten down.
The "SO TASTY!" clip that plays when you successfully cook a Well-Done Steak with the BBQ Spit, or cook one from the last Raw Steak on a Double BBQ Spit.
The sound of a monster crying in pain as it tries to retreat away from the area, signifying that it's almost dead.
The "Quest Complete!" jingle; very satisfying especially if you've just defeated a very durable or verypainful boss.
The unique fanfare that plays when you uncover a Rustshard or a high-grade Charm, or when a Hunters for Hire team comes back with a "Big Success", the latter of which is accompanied by the team of hunters cheering in unison.
Play the Game, Skip the Story: The Monster Hunter world is filled with robust wildlife with unique traits, various habitats and lots of locales, many of which aren't even visited. Looking at the quest descriptions can paint a pretty good picture of the type of society the world is, and how the hunters effect them. There are also various sentient races that aren't monsters, like Wyverians, Felynes, Melynxes and Shakalakas. There are even what are presumably maps of the world at the base camps in some locations. Even the weapons and armors have colorful descriptions, especially in regards to the origins of the weapons or the cultures they come from. But go on any forum and 99.9% of what you'll see is how to fight a monster or where to get what material. All ANYBODY cares about is the gameplay.
Even more apparent with Monster Hunter 4, which was announced to have a greater emphasis on story with the player character being part of a travelling caravan that has various colorful characters. This didn't stop western players from importing japanese copies and not caring a bit about not being able to read one bit of the text.
Try playing the PSP games, where movement is assigned to the analog nub and camera control to the D-pad. The same problem comes back in 3 Ultimate on 3DS, unless you've invested in a Circle Pad Pro for the second Circle Pad and two extra shoulder buttons, or you figure out how to control the camera on the touch screen.
Area boundaries. Players crossing one move to the next area, but monsters don't. This becomes a hassle if the monster decides to stick around out of reach (e.g. due to being exhausted), as it can eat up a few minutes that could be spent whacking the monster to death. You could try ranged weapons, but if you happen to slay the monster while it's beyond the boundary, or break off one of its parts and that part ends up landing beyond the boundary, say goodbye to your carves!
The lack of online multiplayer for the portable releases up until Monster Hunter 4 means that if you don't have local friends to hunt with, you may as well pretend that the multiplayer component doesn't exist. This can make some quests nightmarishlyhard; see Goldbeard Ceadeus below for an example.
The most common reaction to Khezu and his cousin Gigginox. Even the Japanese title of Gigginox translates to "creepy".
Conga and it's variants. They basically attack using various forms of Fartillery and Dung Fu.
That One Attack: Almost every monster has at least one, if not more. Some examples:
Khezu: Roar during rage and either a thunder tackle or thunder ball shot. Roar will incapacitate you unless you defend or have High Earplugs. The main problem with Khezu is that they are unique in having no eyes, so they can't technically see you and thus cannot give you the "spotted" status, and you can only do panic dives (that render you invincible; which regular dodge rolls don't do) in this state. Dodging its attacks at the last second is a no-go as a result.
Gravios: Roar and heat beam. Same as above. High and G-rank one-up this and give the Gravios' a sweeping heat beam. 4 introduces a pattern of heat beam going vertical from its belly, catching many unfortunate hunters off-guard.
Plesioth: Hip-check. HUGE range, fast and with an absurd hit-box (as in, no part of the Plesioth can touch you and you will still get hit). This was fixed in 3 Ultimate though.
Rathian: poison tail backflip. For the beginner, this attack is devastating if you are not used to it. It comes out quickly and with little warning, it has high knockback, and poisons you as well. Luckily, if you have the poison-negating Wroggi Armor, or can just dodge well, it's much less threatening. The Pink Rathian's version is even worse, as it can use a hovering maneuver to position itself right next to you, then immediately backflip. Problem is, it's very hard to tell where the attack will come from, making blocking or evading it very difficult.
Rathalos: High-dive claw attack. Comes almost out of nowhere to the inattentive player and is just as impossibly hard to dodge. Fortunately, a running dive can evade it (you need to see it aiming itself at you first, though, which is the big problem) or you can block it (yes, even with the Sword and Shield!). Failure means you will be poisoned and likely stunned - on top of the huge damage. There is also a sudden fire attack it will do when it suddenly flaps its wings and shoots a burst of flame at you while jumping backwards. There is absolutely no warning, blocking it is difficult, it can turn left or right (meaning it can still hit you if you're attacking it from the side), and it inflicts Fireblight, which can be just as bad as poison. It also sends you flying, and Rathalos jumps backwards as he uses it, so he can now get a free fireball shot at you.
The Deviljho's breath attack (Inflicts huge damage and Dragonblight).
Pearl Espinas: The Firestorm. It essentially flies up and nukes the battle area, spreading unblockable, poisonous flames around it. Get hit by that, and you have a few seconds before it sends out a shock wave clearing everything around it. And it's the main attack this thing uses. Made worse by the fact that making it flinch during the few second gap where it's preparing to jump is the only way to get a much-needed item from it.
Nargacuga's Tail Slam. It's basically a close range, spammable One-Hit Kill that can be frustratingly hard to roll through and has a kinda iffy hitbox (you take full damage even if you touch the dust cloud it raises after the tail touches the ground). Granted, you can see it coming from a mile away (he roars very noticeably before doing it), but not even Evade+2 can bypass it.
Qurupeco's monster calls. If you don't have dung bombs, this turns a one-on-one fight with a relatively easy monster into a two-on-one with anything from the relatively easy to manage Great Jaggi or Rhenoplos to the crap-your-pants scary Rathalos, Diablos or Deviljho. It can then boost their attack, defense and even heal them with other calls, as well as itself.
Uragaan's mighty seismic chin can count if you aren't watchful. It will blow up any rocks thrown by its tail swing, meaning that if you didn't pay attention you have a chance of flying through the air right now, and it's actual damage and flinch radius are questionable until you've faced it enough. Note that the flinch radius will force you to put away your weapon, meaning that you have to draw it again and it just ruined any charge you had going. Also the roar, while not annoying, is followed directly by an attack in front, meaning that you need a certain skill or you have no way of avoiding it if you were in front.
Brachydios's leap slam, especially when enraged. It does a LOT of damage, is difficult to evade, has a wide area of effect when in rage mode, causes Slimeblight, and usually comes out of nowhere as the tell happens only a split second before it goes airborne. And sometimes it skips the tell and jumps without warning. Any of it's new attacks it uses while in Rage Mode can be this. Aside from the above, special mention goes to it's two attacks where it sticks it's horn in the ground. One, where it creates a series of explosions in front of it, does huge damage and has deceptively large rage, and can't be avoided by leaping away from it. The second one, is where it stays stationary and slams its horn into the ground, making spots on the ground around it light up before exploding. This comes with little warning, the spots are hard to see when your next to it, and if you are in the middle of an attack animation you will most likely not have enough time to position yourself in-between them.
The Sand Barioth's tornado. Unlike the normal ice cyclone the normal Barioth uses, this one lasts much longer. Also, the Sand Barioth can fly into the tornado and lunge at you in an instant. This is almost guaranteed to catch you off guard, and unless you're on the opposite side of where it lunges, the only safe way to dodge it is a well timed panic dive. And in G Rank, it can also shoot mini-tornadoes that move through the area.
Normal Barioth has a rather questionable hip check. Though not nearly as legendary as Plesioth's, you can be on the opposite side of the hip check and still get hit and fly in the other direction. Not to mention how, when preparing the hip check, it can somehow rotate on the spot to aim at you, making it even harder to simply run away.
Rajang in 4 will fire its mouth beam with a notable warning (it stands up and aims at the sky first), but now it can aim at any direction without reducing its range and damage.
The Tigrex line most of the time. Very fast, massive range, massive damage. These all increase in Rage mode. Compared to other bosses leading up to it, Tigrex represents a massive spike in the difficulty. Portable 3rd has a Black Tigrex which is basically an even faster and stronger version of the original. The Rare Tigrex in 4 is basically a Tigrex on steroids: crazily fast when fully enraged, spreading explosive powder everywhere (which inflicts Slime status on contact), and being hit by it (enraged or not) is basically a death sentence.
Another frequent candidate is Rathalos, especially from Tri onward since he spends much more time flying just out of reach for most bladed weapons. And its dive kick (see That One Attack above).
Also in Unite, the Nargacuga. A souped-up Tigrex who can shoot tail spikes. Or worse, a Tail Slam that can send you back to the camp in one hit. Green Narga from Portable 3rd is able to do the Tail Slam TWICE in a row. Its spikes will also paralyze you. And 3 Ultimate has a rare species of Nargacuga, which can turn invisible during the fight, and its spikes are poisonous and can shoot them anytime after it uses its tail for an attack. And as if that wasn't bad enough, it's able to unfurl its tail spikes at will instead of needing to be in rage mode to do so.
Khezu. It lulls you into a false sense of security with its slow movements and easily telegraphed attack patterns, but its got a metric fuckton of health, is ridiculously resistant to damage (don't bother trying to attack it unless your weapon's sharpness is in the green), and once you finally do get its health low, it busts out the most devastating enraged mode you've seen up to this point, utilizing a new lightning charge attack that can easily One-Hit KO you and its attacks become much more quick and unpredictable. Made so much worse when fighting it near Snowy Mountain's ledges.
White Monoblos. Not the normal one. The White one. Why? He has more health than his cousin, and he runs away every 5 freaking minutes. Also, he hides in the ground every 10 seconds, rendering him invincible unless you carry the maximum number of Sonic Bombs, which is 10. And it's not enough. Best thing? With the best Sharpness you could afford at first, the only part you could attack properly was his tail and his horn... both of which snap off after only a few hits.
Rajang. Has all the elements of speed and unpredictability of a Blangonga, the roar knocks you away, and it fires LIGHTNING BEAMS and THUNDER BALLS (both are actually non-elemental) from the mouth. Once it's enraged, it'll be difficult not to be hit by its attacks or risk One-hit KO. Unite introduces a type of Rajang that is ALWAYS IN RAGE MODE, and another rage mode upon that (though actually slower). Worse, the best Thunder-element weapons (to deal with Tigrex, for example) can only be made with some Rajang materials. If you're playing MH Frontier then youˇll likely meet a Rajang with red aura.Suddenly the normal Rajang (or any other monster) looks tame in comparison. insane speed, hitbox and attack power that simply murders the whole party in no time. It's so bad, so hard that during a period when an exclusive quest was available to those HR/SR 999 hunters hunting this particular beast (with every quest's data recorded officially), the overall success rate is 5.8%. Out of 270,000+ tries. What makes Rajang worse in 4 Ultimate is that it now uses a more random movement pattern, to a point that it's very hard to predict its next move, unlike the previous version of it.
The lesser mentioned One-Horned Diablos, aka Devil Diablos. It looks like any other Diablos, just slightly bigger and with a broken horn but it's actually a rank above what you're capable of fighting when you can first battle it, which means it hits a lot harder and has a lot more hp and, of course, the game doesn't give you any kind of warning as to what you're in for. You also get the usual items and only a slightly higher reward for defeating it.
Tri has Rathalos (which has been turned from a nonissue in Unite into a genuine That One Boss thanks to a combination of newfound speed and maneuverability and harder access to weapons fit for fighting him) and Barioth, who is basically Nargacuga but stronger, and who exchanges the ability to shoot tail spikes for being able to spit twisters at you. Twisters that freeze you solid. Rathalos and Barioth are especially frustrating because of the low availability of fire and dragon weapons early on. Rathalos goes down rather quickly with an upgraded Rusted Weapon with the Dragon element, which can be mined at a very low chance from the Volcano. Barioth is much easier to deal with with a good fire damage dealing weapon. The catch is that most fire-based weapons require Rathalos parts and upgrading a Rusted Weapon requires Frost Sacs from Barioth.
Chameleos. Probably the most irritating enemy in the series simply because it is invisible for maybe 90% of the time you fight it. Also, just like the Gypceros, it can steal items from you and you can't get them back, and it can do so at range with its tongue, and you likely won't see it coming since it'll probably be invisible when it does it. It also tends to go back into stealth within 10 seconds of bringing it out of stealth and, all in all, a huge pain in a the ass.
Try to engage a high-rank Qurupeco. It can summon the Great Jaggi, or the Rathian. It can also summon Deviljho, who is just as bad as he sounds. Many a Qurupeco quest has ended because it summoned G.I. Jho. And then in 3 Ultimate, there's a unique Deviljho roaming around in G-Rank quests. And it's always in rage mode. Want to run away from that? You HAVE to farm them because they contain a unique type of carve to make good stuff with.
Portable 3rd introduces Zinogre, which looks easy in its normal state, until it starts to charge up 3 times. And it goes into Hyper Electrified mode. It is its rage mode which will not stop until you make it fall down, which means it can stay in this form much longer than others' rage mode. In this state its speed and power rockets to crazy levels, has attacks to make you more vulnerable to thunder-element attacks and fainting, and has a ridiculous hitbox for its attacks. And the paralyzing trap you were using all along is useless, as it's immune to that in that state, and at other times the trap WILL help it to charge up. Also, it can go into rage mode, while already in this mode. Which makes it a Double Rage Mode. 3 Ultimate introduces a subspecies of Zinogre, which can rain down dragon-element thunderbolts while charging up, and is able to launch homing thunder balls at you. And they're fast.
A new contender of That One Boss arrives in 3 Ultimate: Brachydios, also known as "the most powerful package monster" throughout the series among fans and developers alike, which is saying something. It is very fast and agile and its arms are developed enough to throw punches that will leave what amounts to green napalm on you. Unless you rub this slime off by rolling, it will explode after a while or upon being hit by another slime-inducing attack For Massive Damage. Brachydios also uses a moveset very different from that of other Brute Wyverns, and its leap attacks are notoriously deadly. Once it goes berserk the slime on its body turns yellow and detonates on impact, making it one of the most lethal rage modes in the series. Inexperienced hunters are actually advised to just run away from an enraged Brachydios. And then 4 Ultimate introduces a more powerful version of it. Of course, beating it will allow you to create new weapons endowed with the Slime status (see Game Breaker).
Goldbeard Ceadeus, the Elder Dragon you have to slay to unlock G-Rank quests in 3 Ultimate. The good news: You have 50 minutes instead of 30 or 35, unlike the original Ceadeus. The bad news: Note that we said "slay", not "slay or repel"; you must kill it within the time limit or you will get nothing. It also will not retain any damage for successive quests; it starts at full health every time, so you must kill it in one go, and it has the durability of a planet. While managable in a multiplayer hunt, doing this quest solo is nearly impossible if you don't have a weapon that can do damage fast enough or manage use of the ballista and Dragonator weapons effectively.
In G Rank missions, Gigginox gains the ability to lay egg sacs on its back. This happens very quickly and is impossible to stop. Unlike the other egg sacs, Giggi spawned from this one will immediately jump at hunters from the egg sac itself. These Giggi love to jump out while you're in the middle of an attack, and they'll still latch onto you even if you block them. A player with multiple Giggi leeching off of them will lose health very quickly, making slow weapons incapable of rolling a very poor choice in these fights. While the egg sac can be destroyed, that won't stop the Gigginox from laying another one, sometimes while it's on the ceiling. Even the developers seem to be aware of how difficult it is, as missions against a G Rank Gigginox are one of the few G Rank missions that take place in stable environments, so players at least don't have to worry about another boss monster making it even harder.
In 4, any monsters infected by the Frenzy Virus becomes one. Yes, even for those monsters which you've been familiar with. And that's before going to the new monsters in 4. 4 Ultimate takes the idea to anextreme by two words: Extreme Status. Monsters in this state will COMPLETELY nullify traps, elemental damage and status effects, no hunters can ride it, but different parts of the moster will be hardened to a point that all melee attacks will be deflected (even with Fencing skill)! The solution is to carry Purification Stones for a temporary reversion, which is probably unknown to those hunters who doesn't play the story far enough. And two of the confirmed monsters which can enter this state are Rajang and Seregios.
Nerscylla, a horrifying spider which spends 90% of the time swinging around, up and down the webs, making players very hard to catch up with its speed, let alone hitting it (especially when it hangs itself upside down). It can also get you poisoned or put you to sleep.
Even for introductory monsters to the G Rank, Tigerstripe Zamtrios in 4 Ultimate is just too strong. It can now inflate its size at will (while reducing chances for hunters to attack it), then hop and roll around in an unbelieveably fast speed, massive damage included. Its normal state is also very fast. The worst? Most of the time you'll face it in a certain tight area in the desert.
The first fight against Gore Magala in 4. Unlike most of the fight in the series, you actually have to fight it upon the ship like you fight Jhen/Daren Mohran, despite it's just a wvyern-sized monster (now recall how big the ship deck is); worse, it's actually part of the main plot (introducing the Frenzy Virus) so you have to beat it before moving on. Savvy players may notice those extra warning made by the crew, but few may see that Gore's indroduction isn't just a cinematic. It's no less difficult in subsequent fights either.
From Tri, "Heat Exhaustion", one of the 5-star Moga quests. It requires you to transport two Powderstone items, all the way from the peak of the Volcano map back down to base camp. Since Powderstone is a transport-mode item, you can only carry one at a time. To make matters worse, "Powderstone is extremely hot!" That is, it will constantly sap at your health, regardless of your Heat Res stat. You can't put down the Powderstone to attack or use items (e.g. your Mega Potions), as that causes it to blow up, and unless you have certain skills on hand, getting struck by an enemy also causes the Powderstone to drop. There is a shortcut you can take from the Peak, but it involves a drop and thus will break your Powderstone unless you have a skill that prevents damage to transported items in a fall (e.g. Felyne Lander). And this quest has an Unstable environment, meaning that you could be running on your merry way from area to area, with no apparent large monster activity on the map, and then Uragaan appears in front of your face.
Tri Ultimate has "Sticky Situation", the Urgent Quest for Hunter Rank 6. Brachydios is already considered to be That One Boss on its own; however, Sticky Situation throws TWO of them at you at once, and the G-Rank variants of them, no less. While this is already bad enough, the fact that the fight takes place in the Tundra makes it worse as two areas of the map are inaccessible to either Brachydios, which means that they will be crossing paths frequently, even if you chase them off with Dung Bombs. This is particularly frustrating because Brachydios are highly dependent on Splash Damage, ensuring that any crossfire between the two ensures that you'll be treading through a minefield, especially if one (or both) become enraged. And to put the cherry on it, one of the Brachydios is bigger than usual, which means that it's even harder to evade the nearly ceaseless barrage of attacks. And unless you can find a group who has already surpassed it and can help you grind higher rank G-Rank quests, it's not like the gear you'll have the first time you'll do this quest will be all that strong for this, either.
The "Siren's Song" quest, also from 3 Ultimate, is the last 6-star Moga quest, and one of the most annoying. You have to defeat at least two Qurupecos within the 50-minute time limit, AND the Qurupecos in this quest can summon the Deviljho if given the opportunity, forcing you to waste time trying to separate the Deviljho so you can fight safely. The first time you encounter this quest, it's possible to run out of time because your equipment will likely give you only just enough power to capture two Qurupecos.
There's a quest in 4 where a quest requires you to hunt a Deviljo and a Rajang at the same time. Have fun.
Woolseyism: The subspecies of a monster in the Japanese versions usually just adds "subspecies" (亜種) to its name, but the localizations make their names more descriptive to add flavor. For instance, "Lagiacrus subspecies" (ラギアクルス亜種) thus becomes Ivory Lagiacrus due to its distinct white scales.