William is a bipedal, feline Pokémon with a muscular build. He has a short snout with a small pink nose, bright green eyes with yellow sclerae, and tiny, pointed ears. Large tufts of red fur extend from his cheeks, and much of his face is also red. The upper half of his muzzle and the top and back of his head are black. A thin red stripe runs the vertically along his head to his snout, where it splits into a V-shape over his eyes. His torso is gray with several black stripes; the front and back both have a single vertical stripe up the center, crossed by two horizontal lines. Around William's waist is a belt formed from flames that somewhat resembles a championship wrestling belt. In the front center is a small, yellow flame shape. The arms, legs, and tail are all red with black stripes forming bands around them. The arms have three stripes, spiky tufts of black fur over the shoulders, and large five-fingered hands with white claws and a single light red pad on the palm. His legs have only two stripes and simple three-toed paws, and the tail has one stripe and a tuft of spiky black fur around the tip.
Though he makes an attempt to act kind, William does not really care about the troubles of others. He often pretends to be interested, but it is usually clear that he is not concerned. He is usually fairly apathetic, save his enthusiasm for fighting.However, he is also very intelligent and fond of witticism.Quite self-assured, he is certain that he can handle most anything. Though he may appear gruff and tough, he has a major soft spot for young children and pokemon.