How to Catch the Three Regis in Pokémon Emerald

Opening the Doors to the Three Regis

Locate the underwater cave. Make sure you have max repels for on the way to the area. The underwater cave is a cave located beside Pacifidlog Town in the Route 134 ocean current. Take note that you will have to stick towards the very bottom of the screen.

Dive into the calm water. It is in a small space of calm water with a dark spot in the middle. Surf to the dark spot in the middle. When asked if you would like to dive, select Yes.

Go where the inscription is and press B. Travel south in the underwater cave. The inscription is on a large pillar at the end of the underwater cave.

Answer Yes. This takes you to the Sealed Chamber.

Use Dig on the inscription at the end of the cave. It's on the north wall when you enter the Sealed Chamber.

Put Relicanth last in your party and Wailord first. This is the order needed to activate the next inscription.

Go through the wall and read the next inscription. Go through the tunnel you just dug and into the next area of the chamber. The go North and read the inscription on the large rocks on the north wall. This causes an earthquake. Then a box tells you it sounds like doors opening far away. You can now capture the three Regis. If this doesn't work go and switch Relicanth to first and Wailord to last and there should be an earthquake.

Capturing Regirock

Go into the Desert above Mauville City. There is a cave with an inscription near the bottom.

Enter the cave and read the inscription. At the end of the cave, you will see the inscription. You must be in the center of the wall.

Use Rock Smash on the inscription. Stay at the wall move 2 steps down and 2 steps left and use Rock Smash to open a passage.

Enter the passage and capture Regirock. Regirock is through the passage. Use a Master Ball to capture Regirock or fight him until his health is low and use a timer ball to capture him.

Capturing Regice

Fly to Petalburg City and go west. It's on the west side of the map. Once you arrive at Petalburg City, go west until you reach the shore.

Use Surf and go southwest until you get to an island. You will eventually reach an island with lots of trees.

Go to the other side of the island and use Surf to travel north. You will reach another small island with a cave.

Enter the cave and read the inscription. The inscription is on the north wall.

Walk counter clock-wise around the edges of the entire chamber. This opens a passageway.

Enter the passage and capture Regice. Regice is on the other side of the passageway. Go through passageway and use a Master Ball to capture Regice or fight him until his health is low and capture him with a timer ball.

Capturing Registeel

Fly to Lilycove City and go west as far as you can. Eventually, you will see a berry patch or just some dirt.

Locate the Ancient Tomb. Go up the stairs, and past the little trainer hiding. Go through the grass and up the second set of stairs. Go past the hiker. The cave is to the north.

Go in the Ancient Tomb. It's in the small rock mound to the north of the hiker.

Go to the direct center of the cave and use Flash. This opens a passageway.

Go through the passageway and capture Registeel. You can capture Registeel with a Master Ball or fight Registeel until he is low and capture him with a timer ball.