Route 224 is located to the east of Victory Road in the Sinnoh region. For the player to gain access to Route 224, he/she has to defeat the Elite 4. Strong trainers can be found in this route along with high-leveled wild Pokemon.
At the end of Route 224, there is a white rock. If you go to this white rock after receiving the Oak's Letter, you will activate an event in which you can go to Seabreak Path, then eventually Plower Paradise, where you can meet and capture Shaymin.
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