i want a simple answer and why..thank you:D
Well shaymin changes form wether its holding the flower or not so if you want to take to B2 but they take off its items it will become normal shaymin if they dont he'll stay in sky form
I hope I answered your question
Shaymin requires a Gracidea to go into sky form between certain hours of the day
Gracidea can't be traded around (I think), so if you trade Shaymin into BW2 in Sky Form it will change back in the end - I'm not sure about this but it's posible you receive it as Shaymin-S but when it reaches a certain point of time or you put it in your PC it becomes normal shaymin and is unable to be transformed back.