You can catch Steelix (Onix's evolution form) on Iron Island and in Victory Road.
Trade Onix with the steel coat item to evolve it.
To evolve onix you must give it a metal coat then trade it and it will evolve
the way you can evolve an onix is by letting it hold a metal coat and trading it to a friend and then making them trade it back onix evolves when your trade parterner receives onix.
well onix can evolve if you have a metal coat is onix has the metal coat on it if you trade it with a friend and you friend gives it back you will have a steelix.
You can't train it to evolve. For an Onix to evolve into Steelix it must be traded while holding Metal Coat.
Onix and Scyther.
get the metel coat give it to onix and then trade it
Onix does not evolve by level. It can evolve by being traded while holding metal coat.
In order to evolve Onix in Pokemon Crater you must beat Cynthia. After beating Cynthia she will give you the mental coat to evolve Onix.
A metal coat makes an Onix evolve into a Steelix.
You need to give ONIX a METAL COAT to hold. Then trade him and he will evolve into a STEELIX.
Onix can be evolved by placing metal coat on it and trading it with a friend. It will evolve into a Steelix.