How do you Mystery Gift a Manaphy egg from Pokemon ranger2 on to Pokemon Platinum?

This is a simple process. Just follow these steps:

You can not get manaphy any more from Ranger 2 because it was a Wi-fi event and ended in February. If you had got the mission you first beat it and get the egg. Then you turn on Ranger net and go to transfer a Pokemon and then just follow the steps on the screen.

I do not think you can use it on Platinum but you can still try these steps.

Good Luck, Hope this helped.