Things You'll Need
Instructions
Slide the "Action Replay DS" cartridge into the Nintendo DS and then put the "Pokémon Pearl" cartridge into the Action Replay cartridge.
Press the "On" button on your Nintendo DS to bring up the Action Replay DS menu. Click on the "Game List" menu, search for "Pokémon: Pearl," highlight it and press the "A" button.
Highlight the "Add New Code" option and press "A" on your Nintendo DS.
Enter "Professor Oak's Letter" into the first text box and then press "A." On the next menu, enter the following cheat code: "94000130," "FCFF0000," B21C4D28," "00000000," "B0000004," "00000000," "0000AA3C," "EDB88320," "2000AA68," "00000009," "D2000000" and "00000000." Press "A" to save the cheat code.
Scroll down the list of codes until you reach the "Professor Oak's Letter" cheat and press "A" to enable it. Press the "Start" button on the Nintendo DS to start your Nintendo DS.
Load your saved game and then press "L" and "R," simultaneously. Walk or fly to any Poke Mart and talk to the male in front of the cash register. He will give you Professor Oak's Letter.
Walk or fly to the Elite 4 and then use a water Pokémon to surf to the North and ride the waterfall. Surface on the rocky terrain and walk up to Professor Oak. Give Professor Oak the letter to open SeaBreak Path.