if you finished the sinnoh pokedex and a story will happen then you'll get the national pokedex and oaks letter! i hope this helped you!!! :D
you use a action replay and use it to get oaks letter
Event or cheat
go to a Nintendo event.
u need oaks letter that's where shaymin is get oaks letter.
No. The Shaymin event (oaks letter) in Pokemon platinum is not shareable. ~Bellafuzz
oaks letter
You get it over mystery gift.
No. You can only get it by mystery gift.
only with a event
take it to the rock up there by the Pokemon league
You can only get it by using the Action Replay currently. The event for Oak's Letter has expired.
No, you'll need the Action Replay now to get it.