Riolu is a small, blue, dog-like Pokémon. Its legs and torso are coloured black. Riolu's tail is blue and it has a yellow collar. There are rounded bumps on the backs of Riolu's forepaws, which could be the beginnings of the spikes on Lucario's forepaws. Riolu has a black "mask" and red eyes. Like Lucario, Riolu stands on its toes instead of its entire foot.