Mabosstiff is the Boss Pokémon. It is a dark type found in the Paldea region. It is gentle and friendly, but very protective of others.

Mabosstiff is a large, canine Pokémon. Its coat is primarily gray, with blackish gray colorations on its underside, back, and around its face and eyes. It also has a stripe of light gray fur running down its spine. The stripe starts at its forehead, which forms the appearance of slicked back hair; and ends at its rear, forming a long, brushy tail. According to Arven, Mabosstiff is known to shed its fur frequently.

Mabosstiff's head is large with no discernible neck, and contains small orange beady eyes, light gray eyebrows, additional light gray accents under its eyes, a rounded triangular orange nose, and a mouth filled with sharp teeth. Mabosstiff has a large dewlap below its mouth, which allows it to store energy to drive back opponents.

Contrary to scary appearances, Mabosstiff has a kind and gentle heart. The gentle Mabosstiff loves playing with children. However, it will bare its teeth and take on an intimidating look when protecting its family. Mabosstiff will relentlessly chase down and permanently put down any foes that dare threaten its family.