Embedded Tower
3 Pokémon can be caught at Embedded Tower in Johto.
Found on Route 47 in HeartGold and SoulSilver, the Embedded Tower is where Groudon or Kyogre, and later Rayquaza, rest. The interior changes with its occupant: the floor markings turn red and trace Kyogre's fin patterns when it is present, blue with Groudon's arm patterns for Groudon, and yellow with Rayquaza's body markings when the sky serpent is inside.
