How to Find and Capture Darkrai in Pokémon Pearl

Beating the Elite 4

Beat the Elite 4 Champion.

Go to a Nintendo Event for Darkrai, or the Member's Pass.

Fly to Canalave City if you got the Member's Pass.

Go inside the house on the top right hand corner of the city.

Go to Full Moon Island by falling asleep at the house.

Catch Darkrai there. Beware: He is Level 40, and knows powerful attacks.

Hacking Your Game

Use Action replay.

Select the running through walls code.

Go to New moon Island. Run right from there into the ocean.

Keep right until you reach Fullmoon Island.

Catch Darkrai there.