Lucario is a dual-type Fighting/Steel Pokémon introduced in Generation IV). It evolves from Riolu when leveled up with high friendship during the day). Lucario is a bipedal, canine-like Pokémon with predominantly blue and black fur. It possesses a short, round spike on the back of each forepaw, in addition to a third on its chest. It has red eyes, a long snout, and ears. When its mouth is open, two pairs of pointed teeth, one in the upper jaw and one in the lower, can be seen. It possesses cream-colored fur on its torso and blue fur on its thighs that resemble shorts. It has a medium-length tail of the same blue color as well).

Therefore, Lucario is a Generation IV Pokémon.