Well Done for finding one - they're quite rare!
The item you have 'Metal Coat', will successfully evolve an ONIX into a STEELIX. You can catch ONIXs in many caves throughout Sinnoh, but you can specifically find high leveled ones (about Lv55) in the Snowpoint City Temple after beating the Elite Four.
Good Luck!
-ChipChip
you evolve scyther by trading it when holding a metal coathe evolves when you trade him with a metal coat
diglett evolves into dugtrio, onix is its on Pokemon that evolves into steelix using metal coat.
Scyther evolves to Scizor when you trade Scyther while it is holding a metal coat and when the trade dones Scyther evolves into Scizorgive it a metal coat something like that.
give it a metal coat and trade it
you put metal coat on scyther and trade it
Metal Coat
you evolve scyther by trading it when holding a metal coathe evolves when you trade him with a metal coat
in Pokemon pearl scyther evolves when you give it a metal coat and then it evolves about level 25
Scyther evolves when you give it a Metal Coat (To Hold) Then trade it.NOTE: You will not get the Metal Coat back.
onix evolves in a trade when holding the metal coat
diglett evolves into dugtrio, onix is its on Pokemon that evolves into steelix using metal coat.
scyther doesn't evolve from any pokemon, but evolves into scisor when traded with a metal coat
It evolves two pokemon: Onix and Scyther. Have each hold the Metal Coat then trade them to a friend take them back and you will get a Steelix and Scizor.
Scyther evolves to Scizor when you trade Scyther while it is holding a metal coat and when the trade dones Scyther evolves into Scizorgive it a metal coat something like that.
Scyther only evolves if you trade it and it`s holding a Metal Coat.
Trade a Scyther holding Metal Coat.
give it a metal coat and trade it