shaymin

You can find Shaymin in the flowery path, northeast of the elite four, but you might as well not go see him, because you cannot catch him, or reach him for that matter without an Action Replay. So to sum it up for you, Shaymin is off limits for now, Shaymin is not that good anyways.

You will need to cheat to get shaymin.

I think he is near floaroma town... In a field of flowers.

He can only be got by cheating the game. (Such as using an Action Replay or Gameshark).

Though he can found somewhere around the elite four, but the actual place where is found is blocked and is off limits.

Shaymin is an above average pokemon. His movesets are pretty bad, but good to have along with you. To catch Shaymin though, you must have an Action Replay. If you do have one, turn on the run anywhere cheat and start the game. First go to the very beginning of Victory Road, but do not go inside. Instead, simply walk up to the top, and cross over to Route 224 (I think) on the right side of the two big Pokeball statues. Avoid all the trainers, and walk straight up. You will encounter a shiny rock, which is the start of an extremely rare Pokemon event. Since you have the cheat, you will not need the event. At the rock, walk straight up until you see a mirage of Shaymin in black, and a long flowery road. Go up the road with a bike. It is VERY long. At the top, you will be introduced to a place called "Flower Paradise" (I think again...). In the middle, there is shaymin. Save and approach.

Tbug2007

For one thing you need a action replay.Shaymin is in the flowery path northeast of elite four.

In order to battle Shaymin, you must first obtain the "Oak's Letter" at a Nintendo Event (which are currently held in Japan and won't be held in the United States for a while) or by cheating using an Action Replay. You'll notice that even though it was transferred to your game at a Nintendo Event, or if you cheated to get it, the item isn't in your bag. You have to go in a Poke Mart in any town and talk to the man in a green suit to obtain it.

Now you have to go to Route 224. Obviously, to get there, you must beat the Elite Four and obtain the National Pokedex (from Oak in Rowan's lab in Sandgem Town once you've seen all 150 Pokemon in the Sinnoh Pokedex). If you've already done so, go to the end of Route 224 and talk to Oak in front of the white rock. After some chat, a path beyond that white rock should extend and lead to Flower Paradise, where the level 30 Shaymin can be found.

Shaymin is a legendary grass pokemon. He is located at the route that is behind the Pokemon leage. You will need to either get a cheat or got to a nintendo event or get a cheat to expand the route to lead you to shaymin.