Serebii explains that obtaining Kyogre in ?Pokemon Soul Sliver? is only possible by trading with another player who has already caught Kyogre in ?Pokemon Heart Gold.? Each game has one legendary Pokemon that isn't available in the other game. ?Pokemon Heart Gold? has Kyogre and ?Pokemon Soul Sliver? has Groudon.
Groudon and Kyogre are found at the Embedded Tower on Route 47, according to Serebii. Players gain access to this tower after finding the Blue Orb or the Red Orb. The version of the game that an individual is playing determines which orb that the player receives. ?Pokemon Soul Sliver? players receive the Red Orb, while ?Pokemon Heart Gold? players receive the Blue Orb. Players receive the orb from Mr. Pokemon after they obtain the National Dex and receive a Kanto starter Pokemon from Professor Oak.
According to Bulbapedia, the history of the Embedded Tower dates back well before the events that take place in ?Pokemon Soul Silver? and ?Pokemon Heart Gold.? The tower was built by people who came from the Hoenn region. The goal was to build a tower that connected the land, sea and sky. This is why the tower not only stretches high into the sky but also deep below the ocean floor.