Grimmsnarl is a green-skinned humanoid Pokémon with most of its body covered in dark purple hair, except part of its face, its abdomen, its feet and a small red patch on its chest. Like its pre-evolutions, Grimmsnarl has large crescent-shaped ears with red insides, albeit they are longer on this form. Its long, sharp nose points upward and has a single long red nostril. It has a blue tongue and six teeth protruding from its mouth, the front four of which are flat, two on each jaw, while its upper jaw also has one sharp fang on each side. It has white eyes with red irises and black pupils, and gray eyelids. Its face ends in a small pointy chin.
Grimmsnarl's hands and feet have three pointed digits each. Most of its long hair wraps around its body, except for a lock on each side of its face, a few spikes raised on its shoulders and some locks draping from behind its legs resembling a cape. While being bulkier than its pre-evolutions, Grimmsnarl is more slender than it appears to be, with its hair giving the appearance of a muscular body. It is a male-only species.
While in its Gigantamax form, it becomes much taller and all of its body except its face and chest mark is covered in hair. Its limbs become longer, and its hair now makes up its hands and feet, each with three and two digits respectively. Its eyes are red with white pupils, and the hair from around its neck and shoulders is raised in a pointy collar shape surrounding its head as the two longer rear locks join in a single spike waving above the head. Three red clouds surround the back hair that pointed up.
Grimmsnarl's hair works like muscle fibers and helps enhance its strength. Grimmsnarl is able to move its hair, and uses them to ensnare opponents in a tentacle-like fashion. By using its hair in this way, Grimmsnarl is powerful enough to overwhelm Machamp.
When in Gigantamax form, it creates a powerful drill with its leg hair. This drill can create large holes within Galar's terrain. Thanks to its increased strength, Gigantamax Grimmsnarl can jump over the world's tallest building.
Grimmsnarl and its pre-evolved form Morgrem are the only known Pokémon capable of using the move False Surrender, as well as the only Pokémon, in addition to Impidimp, to currently learn Confide by leveling up. In addition, Grimmsnarl is the only Pokémon capable of using the move Spirit Break and the exclusive G-Max Move G-Max Snooze.
- No Pokémon have the same type combination as Grimmsnarl and its pre-evolved forms.
- Grimmsnarl and its pre-evolved forms are also the only Fairy-type Pokémon to have a double resistance to Dark-type moves.
- Grimmsnarl, Hatterene, and their evolutionary families can be considered counterparts.
- Both are Generation VIII Pokémon evolving once at level 32 then at level 42.
- Grimmsnarl and its pre-evolved forms are male only, while Hatterene and its pre-evolved forms are female only.
- Their final evolved forms are both Fairy-type Pokémon with identical base experience and catch rates.
- Each Pokémon in each evolutionary line have the same base stat total as their counterpart (e.g. Grimmsnarl and Hatterene both have a base stat total of 510).
- Both Pokémon also have a Gigantamax form, a signature G-Max move, and use their body hair as their primary weapon.
- In addition, both Pokémon are based on mythical beings from European folklore and mythology: Grimmsnarl resembles trolls, ogres, and goblins and Hatterene resembles witches.
- Lastly, both are the signature Pokémon of two of the rivals in Pokémon Sword and Shield, Marnie with Grimmsnarl and Bede with Hatterene.
- Grimmsnarl and its pre-evolved forms are the only Pokémon that are in the Fairy and Human-Like Egg Groups.
- Grimmsnarl is tied with Granbull for the highest base Attack stat of all non-Legendary Fairy-type Pokémon.
Grimmsnarl may be based on ogres, trolls, and potentially oni, all large and malevolent humanoid creatures from folklore and mythology that are commonly depicted with grotesque appearances and abundant hair. It may also be based on modern artwork of the Chimimōryō, a general term for monsters of the mountains and rivers, particularly of the large and hairy creatures. Like its pre-evolutions, Grimmsnarl also shares traits with goblins. The fact that its strength comes from its hair may be a reference to Samson from the Book of Judges.
Considering its association with Hatterene, it may also be inspired by the bogeyman, bugbear, or coco, fictional creatures created throughout European cultures to frighten children that do not want to sleep or stay quiet. In addition, it resembles depictions of Grendel, a giant monster from the Old English epic poem Beowulf, described as a "creature of darkness" and known for his immense strength.
Grimmsnarl may be a combination of grim and snarl. The spelling of Grimm- may also indicate Grimmsnarl was named after the Brothers Grimm, a duo of brothers who traveled Europe gathering folklore and oral fairy-tales and cataloging them all into a singular book, Grimms' Fairy Tales. Its name could also incorporate the words gnarly, referring to its mangled appearance or unpleasant behavior; grimoire, a type of spellbook; Grímnismál, a mythological poem in the Poetic Edda; and "grimace", a term for a twisted facial expression which Grimmsnarl bears.
Ohlonge may be a combination of ogre and ロン毛 ronge (long hair).