You catch Onix in Orbeghuh Mines or on Iron Island
Find the crystal onix, make it weak and catch it with your best ball
catch it
Onix is uncatchable in emerald you must get one from firered or leafgreen.
There is no such thing as a Crystal Onix. It only exist in the anime.
You can't catch a crystal onix.
Yes u can catch onix in pearl. hes at stark mountain and in jubilife city just keep on going forward into the cave and he should be in there too.
You can catch Steelix (Onix's evolution form) on Iron Island and in Victory Road.
He only appears in the anime. You cannot catch him in any game.
you can only get it by trading from rife red. :)
In the dark cave or victory road.
catch a onix 1000 times from first to last have no money have 99pokeballs, greatballs, ultreballs and 99max poitions
In order to catch an Onix, you must lower it's HP as low as it can go, preferably to 1%, then use a heavy ball, which you can have Kurt, the old pokeball maker in Azalea town, make. The best Place to easily catch a wild Onix is in the Union cave, but you can also find it in Cliff cave at any time, or you could go to Violet city and trade a Onix for a Bellsprout. Hope this helps!:)