I need it because is an EMEGENCY
It is an event item. you can use it to get shaymin if I remember correctly, but the event is already over, so you can't get it. :(
Oaks Letter was a speical event to catch shaymin. But it was only available from Sept 28 --- Nov 8 2009
Sorry the event is over!!
I think the more interesting question is how did you not see the duplicate question ;)
It would have come up when you asked yours:
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Why was my post hidden?
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