Luxio is a feline, quadruped Pokémon resembling a young lynx or lion. Blue and black fur covers most of its body. Its ears, face, hind paws, and front half of its body are blue, while its hindquarters are black. Additionally, Luxio has a tufty black mane surrounding its face. The mane is longer on the male Luxio, while the fur on the hind paws extends to ankles on the female. The insides of its rounded ears are yellow, as are its eyes. There are two yellow rings around each front leg and a yellow, four-point star on the tip of its tail. Luxio is able to communicate with others of its kind using electrical pulses from its claws. Luxio lives in small groups, and is able to generate powerful electricity by gathering the group's tails together.
Luxio debuted in The Rise of Darkrai, where it was among the Pokémon residing in a garden in Alamos Town. Luxio seemed to be shy, as it hesitated before it ran to Ash and his friends' Pokémon. It later participated in a near-skirmish between two groups of Pokémon, caused by a misunderstanding. Afterwards, it was a bystander during the battle between Dialga and Palkia.
Luxio made its main series debut in Leading a Stray!, where it helped a Wailmer that was trapped in the sewers. As a result, the Wailmer made it back into the ocean safely and evolved into a Wailord.
Platinum was attacked by a pack of Shinx and Luxio in Extreme Luxio. One of them, due to his broken claws, was unable to communicate with his group and was shunned by them. In an attempt to regain his group's favor, he battled with Diamond's Pokémon. Pearl eventually managed to get his comrades' trust and befriended the Luxio. Later, he evolved into a Luxray and joined Pearl's team after being named Rayler.