Bruno's Onix was a wild Onix that traveled on Mt. Hideaway and tried to trample anyone in its path. After Bruno saved Ash after he had fallen into a pit inhabited by it, Bruno eventually figured out what was troubling the Onix. A Sandslash had lodged itself in between one of the Onix' many rocks. After Bruno removed the Sandslash from the Onix, he asked the Onix if it wanted to come along with him, to which the Onix happily agreed.