what level does onix evolve into a steelex?

Onix doesn't evolve to Steelix by level, to evolve a Onix to Steelix you need to give Onix a Metal Coat and then trade it and it will evolve.

It doesnt it must be traded butt the guide for the game says you can catch it in a cave but I havent found it yet

Of course you can here 1!.onix must have any item but rare items like metal coat pheonix of steel master ball rare candy wwbox ancient rock ash's hat slow poke tail 2. Make onix lvl 78 3.ruturn the item you gave him/her(onix) and give him a fight with pkmn trnr red and deafeat elite four battle the giant bellsprout and his level 80-85 when level 86-100 must hold bell root and tada stEELIX !!!!!!!!!!!!!!!

Epic not pikachu needs a thuner stone to evole

Just give him a rock stone

Onix is a Poket Monster that does not evolve by level, but by trade with a specific item. Onix evolves into Steelix at any level possible. Onix just needs to be traded to another player while holding the Metal Coat, you get the metal coat in Soulsilver 2 different ways. 1)Find a magnemite and catch it, there is a chance it is holding one it is etrememly rare to find one that way though. 2)Obtaining the Metal coat from the Captain of the S.S. Aqua in Olivine City after beating the Elite Four of Johto. You obtain the Metal Coat after you entertain the Captains daughter and play a game of hide and seek with here. After you find here you return to the Captain's Quarters and he gives you the Metal Coat. Now that you have the Metal Coat you must put in on your Onix and trade it to another player. Trade with somebody you know, so you can get your Steelix back, and you have your steelix, the earlier you do it the better, I myself was using a level 25 Steelix. Hope this helps to all you lost and confused Pokemon lovers.
Peace, Alphadog3879