Lycanroc did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
It evolves from Rockruff. The form it takes upon evolving depends on the game it was evolved in.
In Pokémon Sun, Rockruff evolves into Midday Form Lycanroc when leveled up during the day.
In Pokémon Moon, Rockruff evolves into Midnight Form Lycanroc when leveled up at night.
Lycanroc is a canine Pokémon resembling a wolf. it's two possible forms: a Midday Form and a Midnight Form.
In its Midday form, Lycanroc resembles a quadruped, brown wolf. It has a white underbelly that extends up around its muzzle and eyes during a mask-like marking. It also has pointed ears with dark brown tips and pink insides, big blue eyes, and a triangular, dark brown nose. There are four sharp fangs in its mouth: two within the upper jawbone and two within the lower. Large tufts of brown fur extend from the edges of its head; three tufts on all sides. A bushy, white mane covers its neck. Four dark brown rocks extend of its mane, creating a shape almost like a stylized sun. The lower portions of this form's legs are white, and every foot has three dark brown claws. It also features a long, fluffy white tail.
In its Midnight Form, Lycanroc instead resembles a slouched, bipedal wolf or werewolf. It has short red fur with white on its lower legs, and a white streak that covers its face, underbelly, and tail. It additionally features pointed, button ears with black tips, three large tufts of fur on all sides of its face, a triangular black nose, and a mouth filled with sharp teeth. While the sclerae, irises, and pupils of its eye are visible, all of them glow a pinkish red and no distinctive colors are visible. A mane of fur covers its back and shoulders, sweeping forward over its head to make a crescent moon shape. On either side of its body, slightly below the shoulders, two small rocks resembling claws extend of the mane. A single, bigger stone projects out of the front of the mane over its head. Each of this form's paws has three black claws, and it's a stubby tail covered in long fur.
In order to avoid needless fighting, the Midday Form prefers to measure alone and doesn't form a pack with others of its kind. However, it's a fiercely loyal partner to trainers that accept it during its unruly stage. In battle, it darts past opponents while attacking them with the rocks in its mane. These swift movements leave many foes bewildered.
In contrast, Lycanroc's Midnight Form is thrilled by battling, and becomes more excited the stronger its opponent. This excitement is what causes its eyes to glow. It strategy consists of closing in on its opponent and inspiring attack, then countering with a strong blow that knocks out its opponent. Trainers which will prolong its power earn its trust, but it despises people who it disagrees with or who attempt to force it to fight.
Accelerock is that the signature move of Lycanroc's Midday form.