Houndstone is a large, skeletal, canine Pokémon, reborn from a lovingly mourned deceased Pokémon. The top of its head and its humped back are covered in long, shaggy, white fur that is a light purple color at the base, covering its eyes and its body. Its face has a large, protruding lower jaw, and its legs have three toes each. Below its fur, its legs and tail do not appear to be attached to a torso, instead floating in place relative to each other.
Atop Houndstone’s head is a large protuberance highly resembling a tombstone, which it prefers not to be touched. Houndstone spends much of its time buried below the ground, particularly in graveyards, with only its "tombstone" visible. Houndstone is considered the most loyal of all dog Pokémon. It predominantly lives in boreal mountains.
Houndstone is the only known Pokémon capable of learning the move Last Respects by leveling up.
Houndstone may be based on various long-haired dog breeds such as the Briard or the Catalan Sheepdog. Houndstone's skeletal appearance and typing may be based on depictions of the undead. The protrusion on its head resembles a headstone and a bone, while the raised portion of its body resembles a tumulus, a pile of earth placed over burial grounds. Houndstone may also be based on various of the numerous dogs from Spanish mythology and folklore, such as the Pesanta or the Dip, dog-shaped spirits from Catalan mythology known for draining human vitality.
Houndstone may be a combination of hound and headstone.
Hakadog may be a combination of 墓 haka (tomb) and dog.