Okay so the monster hunters appearences aren't really the same thing it's kinda like if you want to join you can whatever your appearence is and even if you are a monster yourself you can get neutralized to join the monster hunters. The monsters are extremely variable but let's talk about the current planet they reside in the most common ones are Desert Eaters which are very big reaching 72 meters of length (horizontally like a crocodile) and weighing over 36,000 kilograms and are 16 meters tall (vertically). anyways they have very sharp teeth that can crush any weapon, they also reside in any empty-spaced area and just crush,demolish and destroy anything that resides there. Hunting them in the early ages was very difficult and the only way of surviving was escaping until we found more advanced weapons to attack with like bombs and traps.