• English / United States: Crystal Onix
• Japanese / Japan: クリスタルのイワーク
• Japanese (Romanized) / Japan: Crystal no Iwark
• Japanese (Trans) / Japan: Crystal Iwark
• French / France: L'Onix de Cristal

Ash Ketchum and Misty first heard about the Crystal Onix when they picked up a bottle in the ocean with a note in it written by Marissa asking anyone if they knew anything about the Crystal Onix to tell her. Tracey Sketchit explains to Ash Ketchum and Misty that it's supposed to be an Onix made of glass crystal but he said he wasn't sure it was real. Tracey Sketchit states that there were people who said they've seen it but they were only rumors. Ash Ketchum stated at the time he'd love to see the Crystal Onix and his wish came true when he saw it.

Team Rocket heard the rumor about the Crystal Onix from some local merchants and decided they would try to capture the rare Pokémon. The Crystal Onix just hit it with its tail and sent Team Rocket blasting off again.

The Crystal Onix lives on a remote part of Sunburst Island in a cave. When the tide goes down, a sandbar appears to let people get to that part of the island. It isn't afraid of water like most normal Onix are and it often spends time in the underground lake in the cave. Mateo battled it and knocked it out but before he tried to capture it, he felt something strange for a minute when he looked at the Onix. Mateo explained that the feeling was hard to describe but he gained the inspiration he need to start working again on his Pokémon statues thanks to the Crystal Onix. The Crystal Onix then recovered and dove back into the water after Mateo thanked it.