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.

If the reason Onix is so weak is because it was Brock's ace, why didn't they just give it a pre-evolution instead? : r/pokemon

Brock's Steelix, Pokémon Wiki

Brock's Onix Gym Heroes 69/132 Values - MAVIN

ochazuke yokochou — Brock& Onix Sync Move： Rock-Solid Rockslide Brock

Pokemon Explained: Brock's MEGA Steelix

Pokemon Explained: Brock's MEGA Steelix

Brock's Steelix, Pokémon Wiki

Brock's Steelix - Bulbapedia, the community-driven Pokémon encyclopedia

I'm making a Pokemon Game where you fight the Gen 1 gym leaders backward but also changed thinking about reversing the Elite 4 order as well and giving them dual typing to

IF POKÉMON TALKED: Steelix is Happy to See Brock!

Brock's onix evolve into steelix Pokemon in Hindi

In the Pokemon anime, the attack psychic is probably one of the most broken moves there is, being able to take control of just about of any other Pokemon or move. What's