The first encounter

Raikou appears at Bleak Beach during the Pokémon Pokopia main story. Climb to the top of the lighthouse after reaching 100 Bloom Points, then talk to Raikou. That conversation logs it in your Pokédex and makes all three Legendary Dogs available on Dream Islands. You don't befriend it here. That step comes later, on a completely different island.

What to prepare before you go

Dream Islands open up during the Withered Wasteland story arc. Talk to Drifloon to access them from your village. Before you set out for any of the three dogs, unlock Cooking and learn to make Hamburger Steaks. These dishes power up your Rock Smash move, which you need to break through cave walls blocking each dog's hiding spot.

Finding Raikou

Use the Pikachu Doll to travel to Raikou's Dream Island. When you arrive, open your Pokédex right away to check if Raikou has spawned. It doesn't appear on every visit. If it's not there, head back and try again another time.

Finding Entei

Use the Arcanine Doll to reach Entei's island. Rock Smash your way through the lava blocks to get deeper into the cave. Talk to Entei when you reach it, and it will come back to your village with you. You'll also collect 3 Rare Pokemetal from a pedestal nearby.

Finding Suicune

Use the Eevee Doll to reach the Wasteland Dream Island. Go to the rocky central area and enter the cave system there. Follow the path until you hit ice blocks sealing off a passage, then break through them. Suicune is on the other side waiting for you.

The payoff

Once all three dogs live in your village, Pokopia rewards you with the Clear Bell recipe. The Clear Bell is the key ingredient for befriending Ho-Oh, one of the rarest Pokémon in the game. Finding the Legendary Dogs isn't just its own goal. It's the unlock that puts Ho-Oh within reach.