Things You'll Need
Instructions
Play the Game Boy Advance version of "Pokemon" as normal.
Go to Route 120, Route 111 and Route 105 of the Hoenn Region. Enter the caves in each one of these routes to find the three Regis. Battle and capture them. Remove these Pokemon from your party at any Pokecenter and save your progress.
Begin playing the "Diamond" version if you do not have the National Pokedex. View the first 150 Pokemon in the Sinnoh Dex by fighting other trainers, capturing them in the wild or viewing pictures of them throughout the game.
Travel to Sandgem town and talk to Professor Rowan. After the scene, Professor Oak will give you the National Dex and tell you about the Pal Park. Save your progress and quit the game.
Place the Game Boy version of "Pokemon" in the Game Boy slot and the Nintendo DS version of the game in the DS slot once you have fulfilled the requirements of both games.
Turn on the DS system and select the Game Boy Advanced version. On the main screen will be an additional option for trading Pokemon below the "Continue" selection. Choose this option.
Select six Pokemon to transfer to the "Diamond" game. The trade will not work with only three Pokemon, so the other three can be any Pokemon of your choice.
Return to the "Diamond" version and travel to the Pal Park. There, you will receive Park Balls, which have a 100 percent catch rate.
Enter the park and travel to the mountainous area. There, you will find the three Regis in random encounters. Use the Park Balls to capture them, as it is impossible to miss or to run from the battle.