You'll need to catch all three of them before you can encounter the DLC's two new Regis, Regieleki and Regidrago, but they're all sealed away in shrines scattered around the Crown Tundra.

Here's what you'll need to do to enter the ruins and catch the Regis.

Before you can enter the shrine, you'll need to open the door by cracking the following riddle: "Let ring the piercing note that will wake the giant of steel." Although this hint is quite vague, all you need to do to open the door is whistle by pressing the left stick in.

As before, you'll need to solve a riddle before you can gain access to the ruins: "Let the first Pokemon hold a never-changing stone." Simply equip the first Pokemon in your party with an Everstone and interact with the door to open it.

After you've entered the ruins, you'll need to once again illuminate all the dots on the floor to awaken and battle the Legendary Pokemon.

Regice's shrine lies deep in Snowslide Slope, and to break the seal on its door, you'll need to "walk together with a living crystal of snow." To do this, set a Cryogonal as the first Pokemon in your party so that it follows you around on the field.

Once you've caught Regirock, Regice, and Registeel, you can gain access to the fourth and final shrine, which is located in the eastern corner of the Crown Tundra in Three-Point Pass.

Have all three Regis in your party when you interact with the door and you'll gain access to the ruins.

For one, you can only choose one of the new Regis to catch, so you'll need to think carefully before you awaken the giant as your choice is permanent?

There are many other Legendary Pokemon lurking around the Crown Tundra, including the DLC's regal mascot Calyrex, which you'll need to reunite with its loyal steed as part of your expedition?