I want a togekiss.
You can get a Shiny Stone by getting 1st place in the Bug Catching Contest and you can get them at the PokeDome on Monday, Wednesday, Thursday, Saturday, Sunday for 3000 points.
Note: You can only get it after getting the National Dex.
There should be a hole in the fence near the back of the National Park, go through it and go far right until you find a wall, use rock climb and get a Shiny Stone.
Note Rock Climb is only available after beating Blue.