Luxio is a feline, quadrupedal Pokémon resembling a young lynx or lion. Blue and black fur cover 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 blue coloration on the hind paws extends to the 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.
When facing an opponent, Luxio extends its claws in preparation, which can unleash 1,000,000 volts of electricity. Even a slight scratch from these claws is enough to cause fainting. Besides for attacking, Luxio also uses its claws to communicate with others of its kind, by resting them on the others' forelegs and sending electrical pulses through them. Luxio live in small groups and are able to generate powerful electricity by gathering the group's tails together. Luxio are known to be kind enough to share the spoils from a hunt to its own kind.
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 before rejoining its pod.
Platinum was attacked by a pack of wildShinx 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.
Luxio appears to be based on an adolescent lynx or a male lion. It may have also been inspired by the mythical sphinx, as its short face, human-like ears, and cat-like appearance are similar. It may have also been inspired by the constellations Lynx pr Leo, due to Luxio's cat-like appearance and the fact that it bears a signature star shape on the end of its tail. Additionally, the Lynx constellation got its name from the fact that only the lynx-eyed, that is people with very good sight, could see it, alluding to supernatural sight of lynxes.
Luxio may be a combination of lux (Latin for light), lynx, and lion or leo (Latin for lion). Incidentally, the Karnak temple complex in Luxor, Egypt has a famous avenue of sphinxes.