You have to obtain them in HeartGold or SoulSilver by making them with acorns. Attach them to a pokemon then trade it over.
the master code must ALWAYS be turned on it makes all the others work
regular codes don't to be there
ANSWERIgnore the "answer" sign, but, you will need the HMs: surf, and rock climb. You need a master ball, so don't use it like me on uxie or azelf, so i traded a pichu lv 52 for the dialga, but i already used an a.r., I know how to catch every, every Pokemon in diamond version, so ask on!
I am afraid you cant get it at the moment there is only two ways to get the oaks letter along with the azure flute and the membership pass is to go to an event that is giving them away. the other way is to "hack" your game using a cheat device like the action replay however using these devices can seriously ruin your game and sometimes delete your game altogether.
at one time during the year there will be an event going on you go to a gamestop and it has instructions to get oaks letter but you have to have mystery gift.....you click mystery gift then it will say received oaks lette then you go to the nearnest pokemart and a guy will give it to you.....or you can just use gameshark or action replay!! hope this HELPED!!!!
you need the national dex. go to the fight area, and the two people blocking your way north (not the lake) and go up. There will be a fisher dude and he will give you the super rod.