Non-repeatable
- S.S. Aqua - Gift from gentleman for finding his granddaughter
- Power Plant - Trade Lorenzo ♂ a Dugtrio. You will get a Magneton holding Metal Coat.
Repeatable
- Held by wild Magnemite, Magneton, Steelix, Beldum, Bronzor, Bronzong (5% chance)
- Pokéathlon Dome - 2,500 points on Tuesday, Friday, Saturday. (Must have the National PokeDex)
Source: Metal Coat (Bulbapedia)