Uxie is a small, gray, genderless fairy-like Pokémon with two gray tails that are each encrusted with a red gem. These are, presumably, two of the jewels which complement up the Red Chain. Uxie has a partially yellow face with another red gem encrusted into its forehead. Uxie appears to have a yellow helmet that somewhat resembles a human brain.
Main Pokémon games
Uxie first appeared in the Nintendo DS video games Pokémon Diamond and Pearl where it played a prominent role along with Azelf and Mesprit. After saving it from Team Galactic, the player would be able to find Uxie in Acuity Cave. During the battle the player will be given the chance to capture it. If Uxie faints in battle, they will not be given a second chance and the only way to come into a possession of one after this is to do so through a trade. A couple of years after Diamond and Pearl were released, GameFreak developed a remake titled Pokémon Platinum in which Uxie and the two other psychic Pokémon played a similar role.
Other Pokémon games
Super Smash Bros. series
A trophy of Uxie is present in the Wii video game Super Smash Bros. Brawl. The Pokémon is one of the many different Legendary Pokémon that appear on the stage Spear Pillar, though unlike some of the species Uxie will have no effect on the gameplay when it appears. The following is Uxie's trophy description in Brawl:
"A Knowledge Pokémon. It's said that Uxie's emergence gave humans the wisdom to improve their lives. This Pokémon possesses the ability to erase the memory of those who see its eyes. Uxie uses status-altering moves in battle--its frequent use of Yawn is very effective in putting foes to sleep. Uxie makes its home in Lake Acuity in the Sinnoh region."