In Alola, Marowak has a regional variant that is Fire/Ghost. It evolves from Cubone when leveled up at night starting at level 28. All Cubone in Alola evolve into this form regardless of their origin.
Marowak is a bipedal Pokémon with a spike located on its tail. On its stomach, Marowak is very light brown in color, as opposed to most its body, which is a darker brown. Two small claws, one on each hand, serve as its thumbs, and two large nails make up its toes. Marowak's head is composed of the skull it once wore as a mask. It can no longer remove the skull, as it became a part of its body. Marowak's jaw is composed of bone, and its nostrils are located on the nose of the skull. Its triangular eyes are brown and are also located on the skull. Marowak is well known for ferocity with its bone club, which it is said to collect from a hidden graveyard. It and its pre-evolution, Cubone, are the only known Pokémon that can learn Bone Club and Bonemerang.
Upon evolution, Marowak has overcome the grief of its mother's passing. Now ferocious and violent, Marowak is an adept combatant, and uses the bone it carries as a weapon and a boomerang. Marowak has also been recorded pounding on boulders with the bone club it carries in order to tap out messages to others. It lives in mountains to test its skills.
In the Alola region, Marowak was faced with an abundance of its natural enemies, Grass-type Pokémon. This harsh environment led it to bond closely with its friends, which is said to have created a sort of sixth sense and caused it to take a new form. Alolan Marowak rubs the bone it wields against its forehead to light the ends in a green flame, and then twirl the flaming bone. It specializes in an attack where it releases a weak ball of flame from its bone that will relentlessly pursue its foe. Alolans would fear it for a conjurer, due to its rarity and the fearful sight of it dancing with its bone. Alolan Marowak's body is black, and its skull has a dark, flamelike mark between the eyes. Its eyes are also a pale gray. Compared to regular Marowak's squatter, thicker body, Alolan Marowak is relatively thin, making it lighter. White markings echoing shoulder blades, vertebrae, and hip bones also line its back. The bone Alolan Marowak uses is longer than the one regular Marowak uses. Alolan Marowak is the only known Pokémon that can learn Shadow Bone.
Marowak first appeared in Bad to the Bone under the ownership of Otoshi, who had recently got his GymBadges stolen by Team Rocket. The Marowak left Otoshi because it felt that if he lost his Badges, he lost the respect Marowak had for him. Marowak finally decided to come back and help its Trainer when he battled Team Rocket to get his Badges back.
Pokémon Red, Blue, Yellow, FireRed, and LeafGreen: Marowak was killed by agents of Team Rocket, leaving a Cubone as an orphan. With the Silph Scope, her ghost could be seen in Pokémon Tower. It can only be caught by using a cheating device. After fainting in a battle, a message will pop up saying that the Marowak's soul has finally moved on to the afterlife. This message, however, still shows up even if the player actually caught the Marowak with a Gameshark or Action Replay given that the Marowak is not supposed to be catchable.
Marowak is reptilian in nature and may be based on bipedal dinosaurs.
Alolan Marowak's design may draw inspiration from fire knife, a Samoan traditional dance implement. Alolan Marowak also may draw inspiration from the Polynesian concept of mana, a spiritual essence that exists in all objects and people. It also allows people to imbue their "spirit" into other people and objects for protection or vengeance.