Druddigon is a large, blue, draconic Pokémon with medium-sized wings shaped like thistle leaves, although it is never seen flying. Its bright red head is harder than rock and is very rough. It has a set of glaring, ferocious pale yellow irises. Its arms are longer than its legs, giving it the appearance of a hunchback. It has a thick, moderately-sized tail and sharp claws on both the hands and feet. It also has tall, conical, red spikes; three on each arm, one on each shoulder, two on each leg, and four on its tail. It has a blunt, brutal snout, bearing a maw with no discernible teeth; instead, small fang-like protrusions sprout from its jaws. It has a series of olive, ellipsoid scutes running across its belly.
Druddigon is known to be vicious and cunning. It warms its body by taking in sunlight with its wings; if its body temperature lowers, it becomes immobile. It has savage physical strength; it nimbly chases prey around its den, using its outstretched claws to catch them, or charging into them face-first. It infiltrates the tunnels of other Pokémon, such as Diglett and Dugtrio, and waits for its prey to pass by. Druddigon lives in caves, stolen nests from other Pokémon, and is carnivorous.
Druddigon is the only Pokémon absent from Sword and Shield pre-1.2.0 to appear in both the Isle of Armor and Crown Tundra Pokédexes.
Druddigon appears to be based on the red-headed rock agama. Its natural appearance and cave-dwelling behavior also seem to resemble a European dragon. Druddigon's grotesque appearance and ability to become immobile when cold is reminiscent of gargoyles and trolls, both of which turn to stone under certain conditions.
Druddigon may be a combination of dragon, ruddy (reddish in color), and possibly dread.
Crimgan may be a combination of crimson and 顔 gan (face) or 岩 gan (rock).