I just got Oak's letter! Don't know what I'm talking about? On pokemon platnium, from now to Novermber 8th I think, you can get Oak's letter. But you need wi-fi to get it. Any hoo, don't know what Oak's letter is? It's what you need to cathc Shaymin. Don't know what Shaymin is? (Gee, you're incomitant.) Shaymin is a pokemon you can only catch via special events like this one. But you can only catch it after you beet the game, and I'm only up to the fourth gym badge.