Onix

Onix is a non-playable character serving as Brock's strongest pokemon.

Description
Onix basically resembles a giant chain of gray boulders, with a rocky spine on its head. The Pokémon has a magnet in its brain that serves as an internal compass. Onix's body becomes more rounded and smoother as it grows with age. A fully grown Onix measures at an enormous 28 feet 10 inches, or 8.8 meters.

Move Set
0. Mud Sport

0. Tackle

0. Harden

0. Bind

6. Screech

9. Rock Throw

14. Rage

17. Rock Tomb

22. Take Down

25. Sandstorm

Location
As of version 2.4, Onix is not yet a catchable pokemon. He is seen as a boss in Pewter Gym and in Mt. Moon 2