May Mega Evolution Magic

Pokémon X and Y: Best Teams, How to Level Up, Mega Evolutions

Steelix (Pokémon) - The Pokemon Insurgence Wiki

Mega Steelix, Pokédex

Steelix, Pokémon GO Wiki

Elite Trainer Mark on X: Onix was Brock's first ever Pokémon. However, it didn't even evolve under his ownership, it evolved into Steelix while his brother Forrest was taking care of it.

Just 1 Mega Steelix Raid & Mega Evolving Shiny Steelix in Pokemon GO

Favorite mega evolution ( sorry I messed up the first time)

Pokemon GO Mega Steelix raid guide: Best counters, weaknesses, and more

RUMOR: Let's Go! to Add New Mega Evolutions

Onix (Pokémon) - Bulbapedia, the community-driven Pokémon encyclopedia