Within the Flower Paradise is Shaymin - it must be caught, but at a somewhat meager Lv.30 it should be a fairly easy catch if you're prepared for it. It carries the moves Growth, Magical Leaf, Synthesis and Leech Seed, which makes its moveset slightly more catch-resistant due to the high number of healing moves Shaymin packs here.
Two other things of note are that this event is available to players with US copies of the game - that means you don't actually have to be in the US to get the item from Mystery Gift. Finally, taking this Shaymin to Floarama Town will allow you to get the Gracidea item by speaking to one of the people standing outside in the town. Gracidea will allow you to transform Shaymin into its Sky Forme.
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