Byron's Steelix is one of Byron's strongest Pokémon. He is voiced by Unshō Ishizuka in both the Japanese and English-language versions of the Pokémon anime.
Steelix was first seen in a flashback in Shield with a Twist where it was shown battling Barry's Empoleon. Steelix lost the battle.
Steelix later appeared in "Dealing with Defensive Types" where he was the second Pokémon to be called out in Byron's battle against Ash. Despite being at a type disadvantage, Steelix displayed incredible power by easily defeating Ash's Buizel. Steelix then battled Chimchar but Chimchar managed to dodge Steelix's attacks and used Dig to weaken the battlefield. Due to Steelix's massive weight, the ground beneath it eventually collapsed and Steelix was defeated by Chimchar's Flame Wheel.