Steelix is a long, gray serpentine Pokémon. Its body is divided into several gray-colored rocky sections, with blunt gray spikes protruding from three of those sections. It has a huge head, with large square-shaped teeth. Its eyes are red in color.
Male Steelix have two teeth on their outer jaw while females have only one.
Steelix can be obtained by making an Onix hold a Metal Coat and trading it. Steelix obtains a mega evolution in Omega Ruby and Alpha Sapphire.
Brock's Steelix is one of Brock's Pokémon and his father, Flint caught as an Onix in Kanto. It evolved into Steelix and was discovered in Battle Frontier series. Steelix was given to Brock's younger brother, Forrest.
In the Sun & Moon series, Brock's Steelix can Mega Evolve into Mega Steelix. During the Gym battle between Brock and Kiawe, after the latter removed his vest and shirt, revealed a necklace with a Key Stone serves as a pendant. Steelix was able to withstand all of Turtonator's Fire-Type attacks including its Z-Move, Inferno Overdrive, despite being super effective damage. Mega Steelix quickly defeated it using its powerful Stone Edge, while Turtonator used its Dragon Tail to disperse its powerful attack, but failed.
Olivine City Gym leader Jasmine also owned a Steelix. In the Diamond and Pearl series, it was followed by Canalave City Gym leader and Roark's father, Byron also owns a Steelix as it shares its powerful Screech ability with Roark's Onix.