The Gracidea flower wasn't an item in Diamond, and neither is Sky forme Shaymin, so sorry.
Chat with our AI personalities
shaymin sky forme is only available in platinum and gen. 5
dont no kill shaymin
if you go to the lady in the flower shop in goldenrod city she should give you a flower that transforms shaymin into sky forme
55252050 411405225
to get shaymin u need oak's letter then after u catch shaymin go to floweroma tow and talk 2 the blond lady by the pokemart she gives u the flower to change shaymin's forme