How To Get Oaks Letter

Method

Oak's Letter is a special key item that is available for players of the Diamond, Pearl and Platinum versions of the game. You take the key to the end of Route 224, which will open a special area, allowing you to battle and capture a shaman.

Unfortunately, Oak's Letter is not available during the normal course of gameplay and there is currently no way to get the Oak's Letter. It was an event item, released unofficially over the Nintendo wifi network for a limited time. As it designed and released for a past generation of game, it is unlikely that the Oak's Letter will be released again.