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Rayler first appears as a wild Luxio in Extreme Luxio where it was a member of a pack of wild Luxio and Shinx. However its claws were broken and because of it, Luxio could not communicate with his pack members, causing them to shun it. In a desperate attempt to get them to acknowledge it, he kidnapped Platinum and her Piplup so that it could challenge Pearl and Diamond.
After managing to beat Diamond's Pokémon easily, it then fought Pearl's. During his fight against them Pearl noticed its broken claws and quickly came up with a way for it to communicate with its pack, using his comedy Duo act as the base. Being able to communicate with its pack again, it thanked the group and left.
It makes a reappearance as a Luxray in Passing by Probopass and Maneuvering around Magnezone where it helped Diamond rescue Pearl and Platinum, after Cyrus attacked them while they were passing through Mt. Coronet for "defiling" the site of his Pokémon's evolutions. It used its X-ray vision to save one of his pack members, a Shinx. It left again with its pack after helping save Pearl and Platinum.
It returns once more in Maddening Magby where it encountered Pearl at the Fuego Ironworks on his adventure to protect Lake Valor from Team Galactic, where it was revealed to have become the leader of the pack. After helping Pearl rescue the trapped Mr. Fuego, and getting its back burned it the process of saving Pearl from a furnace, it decided to join Pearl on his journey, becoming his third Pokémon. It is there that Pearl decided to name the newcomer Rayler.