Locations For The Other Classic Monsters.

I think Rodan should be found either dormant in a volcano or somewhere underground, possibly under a mine shaft. Mothra should be found on Infant Island, plain and simple. She does not have to be supernatural, but she should be ancient and worshipped by a group of people living on the island. Ghidorah should either arrive in a meteor or  have already arrived long ago and be dormant somewhere and awakened by human tampering.

i think china might be a goodplace for ghidorah to be dormant in. he might be where the legend of dragons had come from

I agree. That might add an intersting dynamic to Ghidorah. Perhaps he had been sighted in China long ago, creating the legend of the dragons and causing his likeness to be imitated in Chinese myth and architecture.

I'd prefer if Ghidorah was park of a race, but kind of like a Siamese Twon, with three heads and two tails. Also, he could've attacked Europe, which started the legends of fearsome dragons that terrorized cities.