Things You'll Need
Instructions
Sealed Chamber Puzzle -- "Ruby," "Sapphire," "Emerald"
Go to Route 134 and use "Dive" under the water to reach the sealed chamber. Make sure you have a Relicanth and a Wailord in your party in the first and last positions, respectively, for "Ruby" and "Sapphire" versions. For "Emerald" version, have Wailord in the first position and Relicanth in the last.
Use "Dig" at the door to open up the path to the next chamber
Read the uppermost inscription to cause an earthquake and unseal the ruins that contain Regirock, Regice, and Registeel.
Regirock - "Ruby," "Sapphire," "Emerald"
Head to the Desert Ruins in the desert on Route 111 after completing the sealed chamber puzzle.
Go to the Braille inscription in the lobby area.
Take two steps to the right and two steps down and use "Strength" if you are playing "Ruby" or "Sapphire." If you are playing "Emerald," take two steps to the left, two steps down and then use "Rock Smash" instead. In both cases, the door to the inner chamber will open.
Enter the inner chamber and challenge Regirock. This is your only chance to catch it, so save first and make sure you have a healthy supply of Pokeballs.
Regirock - "Platinum"
Put an event Regigigas labeled as being found in a "Fateful Encounter" in your party and head to Route 228. These special Regigigas were only available through Nintendo events, so if you don't have one you will either need to trade for one or obtain Regirock via trading or Poke Transfer.
Enter the Rock Peak Ruins.
Step on the seven-dot pattern on the floor and investigate the statue of Regirock. You will be challenged to battle Regirock. As long as you have the event Regigigas you will be able to repeatedly challenge Regirock -- however, you can only capture it once.
Regice - "Ruby," "Sapphire," "Emerald"
Head to the Island Cave on the small island on Route 105 after completing the sealed chamber puzzle.
Enter the cave and read the Braille inscription in the room. For "Ruby" and "Sapphire" players, set the game down for the next two minutes -- the door will only open after two complete minutes have elapsed with you taking absolutely no actions. For "Emerald" players, stick close to the walls and make a counterclockwise lap of the room to open the doorway.
Enter the inner chamber and challenge Regice. This is your only chance to catch it, so save first and bring plenty of Pokeballs.
Regice - "Platinum"
Put an event Regigigas labeled as being found in a "Fateful Encounter" in your party and head to Route 228.
Go to the Route 216 exit to Mt. Coronet and enter Mt. Coronet.
Find the extra room in near the Route 216 exit and enter it to enter the Iceberg Ruins.
Step on the seven-dot pattern on the floor and investigate the statue of Regice. You will be challenged to battle Regice. As long as you have the event Regigigas you will be able to repeatedly challenge Regice -- however, you can only capture it once.
Registeel - "Ruby," "Sapphire," "Emerald"
Go to the Ancient Tomb on Route 120.
Go to the center of the room in the middle of the six pillars. For "Ruby" and "Sapphire" players, use "Fly" to open the door to the inner chamber. For "Emerald" players, use "Flash" instead.
Enter the inner chamber and challenge Registeel. This is your only chance to catch it, so save first and bring lots of Pokeballs.
Registeel - "Platinum"
Put an event Regigigas labeled as being found in a "Fateful Encounter" in your party and head to Route 228.
Go to Iron Island and find the Iron Ruins, which is a cave found near the exit.
Step on the seven-dot pattern on the floor and investigate the statue of Registeel. You will be challenged to battle Registeel. As long as you have the event Regigigas you will be able to repeatedly challenge Registeel -- however, you can only capture it once.