Rylvarian appears to be based on various lizards in particular larger Monitor Lizards, the Pokémon walks bipedally having large albeit short relative to the rest of its body legs. Each leg ends in a five toed foot, each toe has retractable claws that the Pokémon can use to attack with. It has comparatively longer arms which have a spine that juts from the elbow of the Pokémon. It can often be seen carrying around books in its arms, it's unknown where it gets the books although apparently it's been known to steal them from people. The Pokémon's body is covered in very small scales which appear somewhat bead-like in appearance, most of the scales are black in colour although some are also cyan and indigo in colour.
The Pokémon's head and upper body is covered in long hair that extends down from the top of the Pokémon's head in a mohawk-like style. the hair is so long that it extends from the head of the Pokémon down its back and over its shoulders forming what appear like a cloak that the Pokémon wears. The tips of these extremely long parts of its hair are white at the end. The hair covers much of the Pokémon's back and has a silky-black look to it having a sheen in sunlight. Rylvarian has red eyes with a slit pupil and appears to have a constant scowl on its face, interestingly the Pokémon has a large glassy-like scale located directly in front of each eye that allows it to focus when looking at prey. Sometimes the Pokémon will stick out its tongue revealing it has a serpentine forked tongue that is dark blue in colouration.