How do you evolve Onix in Black 2?

Pokémon Brilliant Diamond and Pokémon Shining Pearl Trainers Guide, Raising and Evolving Pokémon, Official Website

HOW TO Evolve Onix into Steelix in Pokémon Sword and Shield

Mega Steelix (Pokémon GO) - Best Movesets, Counters, Evolutions and CP

Pokemon Legends Arceus Onix

After almost 2,000 spins, I finally got a metal coat to evolve my 100% Onyx. Couldn't be happier with the result! : r/pokemongo

Pokemon Onix (61/108) 2016 XY Evolutions - MINT PSA GRADED 9

Onix, Pokémon Quest Wiki

Steelix (Pokémon) - The Pokemon Insurgence Wiki

Pokémon Brilliant Diamond & Shining Pearl: Evolution items

Pokémon Go Metal Coat - evolve Scyther into Scizor, Onix into Steelix, and how to get the Metal Coat