What do I have to do to open the Regi Pokemon Caves?

After you've used dig to open up go to the back of the room. put relicanth in your first pokemon slot, and wailord in the last. Click A on the weird writings. After that there'll be rumbling. That means the regis lairs has been opened. For regirock, go to the desert where there's a sandstorm.

Keep going down, until you see a cave entrance. It is surrounded by four or five rocks. Go in, then go to the middle of the weird writings. Move right 2 spaces, then down another 2. Then use strength. The door'll open.

For regice, go to the island cave on route 105. When you enter, click A on the weird writings, then A again. Wait for about ten minutes, and the door'll open.

For registeel, go to the ancient tomb on route 120. Inside, go to the middle of the room, then use fly. The door will open.

Hope i helped!

So you managed part of the Sealed Chamber. All you have to do is acquire a Relicanth and a Wailord, put Relicanth up front and Wailord in last, and wait for the tremor to pass after you've looked at the back inscription in the second part of the Sealed Chamber.

As for looking for them, you're on your own, or you can look for more of my submissions.

Put relicanth in front of your party and wailord in back. Then talk to the very back message.