Since before Generation IV moves' category depend on the type,and Hidden Power's category is Special,for example if a Pokemon's HP is Ground (which is Physical before Gen IV) will it's HP be Physical or Special?
No, In Gen III, and II, HP was always Physical.
IT is normally that I know of physical course then agai im not the best with hidden power I do beleive it was not determined by type hope this helps slightly at least
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