In Pokemon Platinum you can catch a Giratinia Origin form, but don’t forget your dusk balls!

• On the top of Mt. Cornet, defeat Mars and Jupiter
• Cyrus will summon the two key legendary Pokemon from Pokemon Diamond and Pearl -  Dialgia and Pulkia
• The Giratinia will appear in Spooky Manor, then will disappear
• The screen will turn black, a Portal will appear.  Go inside
• You will help the Azelf, Mespirit, and Uxie by solving the puzzle, get to the end and you will find Cynthia
• Cyrus will show up too, and of course he will want to battle, defeat him
• SAVE YOUR GAME! Because you will soon face a Level 47 Giratinia in it Origin form
• Weaken it and then catch it with dusk balls