Iron Mountain isn't in Pokemon Platinum
You have to hatch it from the egg you received from Riley at Iron Mountain/Iron Island
on iron island in platinum
Mt. Coronet and stark mountain
at iron island
you can get it on iron island
Iron Island
iron island
Its Heatran, and you can get him at stark mountain.
you can find it in stark mountain.
stark mountain
you can get iron plate by using explorer kit
You can get one in iron island