Its eyes remain yellow, but with larger irises which still lack visible pupils. Thundurus's hair remains the same the mustache now takes on a more raised snout and fanged-maw-like appearance, with two curving wisps flowing back and past its ears. The horn on its head is now thicker and extends out more, while its ears become more pointy and pinned back. In Therian Forme, Thundurus is a large, blue, sleek, bipedal snake or dragon-like Pokémon. They are a dark gray color, and each has a long, sharp spike on one side.
Spanning the length of its tail, Thundurus has several ball-like structures. Its lower body consists of a trailing cloud, with a thick, long, curling, purple, cable-like tail. It has two spotted muscular arms, with five fingers on each hand. Its broad chest consists of two joined, purple, rounded-diamond shaped pectorals and its shoulders, elbows and navel are adorned with raindrop like designs. The front of Thundurus's body is covered in various, irregularly shaped purple spots. Its eyes are yellow with beady white irises and no visible pupils. Thundurus has white, zigzagging and jutting styled hair, a spiky white mustache, and two pointed blue ears on either side of its head. On its head is a single, long, sharp, purple horn. It is a male-only species with no female counterpart. In Incarnate Forme, Thundurus is a blue, muscular humanoid Pokémon, which resembles a genie.