Well, you can use a action replay to catch shaymin in the wild but to get the gracadea flower you to a bland girl and she gives it you. You have to get oak's letter (Shaymin Event) for her to give you the gracedea flower. Oh yeah she's in Floaroma town. Go to the front and just walk up to her you can't miss her.
Well, you can get a garcideia flower from this blond hair lady in the flower town( I know what it is called, I just don't know how to spell it) then you can go to the top of mt. Coronet and get shaymin. Once you got Shaymin, use the garcideia flower on shaymin and viola! You got yourself a sky Shaymin!! You do NOT need an acrion replay cheat for sky shaymin in platinum but maybe for diamond or pearl if it is possible.
But anyway, I hope that helped!:D
But anyway, I hope that helped!:D
First pokemon in your pc on plat is shaymin sky forme 94000130 FCFF0000 B2101D40 00000000 E001EE24 00000010 013C012B 014701DE 01480153 01DE0149 1001EE34 0000FFFF 2001F0F4 00000016 E000CF44 00000088 00000001 039D0000 2ED4A865 3F2998C4 65E6D810 7C9F0516 BDFBE3EE 2BBB6F85 97E3C155 B3A1AFAB 4DF92024 75B53D09 757569A7 7036F074 EE2C554E E4D10F7A 94174C41 02A97468 88F4217C E7FC3375 163A5873 A2A7566F 1BC147E3 E23690AC 15DE01A8 3D0C60DD 14F05678 712EED91 52FEB83C F488A9DA 8696F8C3 61D160BE 462501E7 1A0063F2 D2000000 00000000 It's shiny to!Press L+R to activate. I tested it and it works!