For Diamond, Pearl, and Platinum, it's inside Iron Island.
The Metal Coat can be found on Iron Island.
Give it a metal coat and trade it. The metal coat can be found on on five island
You find a metal coat near the memorable pillar on five island.
iron island in the house
metal coat can be obtained at five island near an island to the right of it there is a statue where an onix rests near there is the metal coat, also at seven island there is a trainer tower defeat the trainers on each mode single, double, mixed, and knockout to get prizes such as metal coat, kings rock, dragon scale and upgrade.Head to five island and go east use surf and go south to memorial pillar look around to find an item that's the metal coat.
The Metal Coat is down the bottom of the Five Island area, by Memorial Pillar. Just follow your map.
Get one at Iron island.
A Metal Coat can be acquired outside the Iron Island cave. You can get to Iron Island by talking to the sailor in Canalave City and he'll sail you there.
go inside the house on the island and talk to the guy and he will hand you a metal coat. (i have done this already and i used it on a scyther then i traded my scyther then it evolved) i hope you try that
On five island surf to the right and find the memorial of a dead onix nearby is a metal coat.
go to iron island
you go to the island with the stone pillar. It has a person mourning a deceased Onix. If you give him a lemonade, he will give you metal coat.