I forgot about this puzzle for a while, so I'm coming back to clarify for anyone who is curious.
All of these are
Flying Wyverns, as IT Alex said, a family of monsters from the Monster Hunter franchise.
This refers to Gravios, a massive dragon with skin of stone. Its rocky armor is strong enough to cause all but the sharpest of weapons to bounce off it pathetically, hence "bouncy rock". Its young form, Basarios, also works for this point because although its armor is weaker, it uses it to disguise itself underground, pretending to be a natural rock formation.
Diablos, a desert-dwelling monster with two massive horns. It gores hunters on its horns by charging forward, much like a bull.
This is Rathian, one of the most iconic monsters that uses both fire and poison to take down targets. Her tail contains all her poison, which she administers by taking flight while flipping her tail forwards. Hint 2 and the title text refer to the male counterpart, Rathalos, a very low drop rate item, the Rathalos Plate, and the struggle to find one.
Here we have Barioth, an agile monster with prominent tusks and icy breath. When attacking the player, it will often move around the room quickly through a series of jumps and leaps, rather than walking or flying.
This refers to Nargacuga, which has a similar build to Barioth, but faster and without any of the ice powers. It is famously hard to deal with when enraged, where its eyes will glow a bright red and its tail bushes out into a barbed end, as opposed to its thin and slender appearance otherwise.
Giginox, a poisonous cave-dwelling creature. It is unique in its anatomy, which is completely reversible, allowing it to eat with either its mouth or its butt, much to the disgust of hunters.
Seregios, also known as Steve, is covered in sharp scales that it can fling at unsuspecting prey. Normally, these scales lay flat against its body, but when angry they stand on end in a hilarious fashion that can only be described as "a pinecone".
Tigrex, a tiger-esque dinosaur that leaps and scrambles its way across the floor to charge hunters down. The clue took inspiration from its name, and its general aesthetic.
The Crimson Chin refers to Urugaan, who slams his chin on the ground to create a shockwave, much like the titular superhero. His chin also glows red when enraged, but it is far more pronounced on its variant, the Steel Urugaan. Sick chicken could refer to several monsters in the same family, but the one I had in mind was Gypceros, which spews poison excessively while running around like a chicken. The dog with fleas is Zinogre, a massive wolf that harnesses the power of lightning found in parasites known as Fulgerbugs that infest its back. All 3 of these hints were intended to point out that the family is not Brute Wyverns, Bird Wyverns, or Fanged Wyverns.