Things You'll Need
Instructions
Put the "Pokemon Sapphire" or "Emerald" Game Boy Advance cartridge into slot 2, at the bottom of the Nintendo DS, and put "Pokemon Diamond" in slot 1 at the top.
Turn on the DS and proceed to the "Pokemon Diamond" title screen. Here you will find an extra option to choose Pokemon to transfer from the GBA cartridge.
Select six Pokemon from your "Pokemon Sapphire" or "Emerald" Pokedex to transfer to "Pokemon Diamond." Make sure that Kyogre is one of them.
Start up your saved game in "Pokemon Diamond" and go to the Pal Park area at the end of Route 221 in the south west of Sinnoh. You will be given six Pal Balls as you enter.
Go to the Ocean area at the south east of the Pal Park and use a Pokemon's Surf move to surf on the water. Surf around until you encounter the Kyogre as a wild Pokemon.
Throw a Pal Ball as soon as the battle with Kyogre begins and you will capture it.