Darkrai can be captured, but not by normal means in-game. You used to be able to catch it through a Nintendo event, but nowadays, the only way to catch it is through the use of an Action Replay.
get the members card and go into the house with the locked door
No, the only way to capture Darkrai in Diamond or Pearl is to obtain the Member Pass Key Item from a Nintendo event. At the time of writing, this event has yet to happen. Several Darkrai have been given away at Toys 'R Us in America and Woolsworth's in the UK. Those Darkrai are currently the only legitimate Darkrai.
Pokemon event.
You cannot find the Pokemon Darkrai in Turnback Cave in the game Pokemon Diamond. Instead you can find him in Newmoon Island.
Darkrai is a dark type of Pokemon. You can catch one in Pokemon Diamond version on Newmoon Island but you need a membership card.
You need an event.
No
Darkrai is a Pokemon from Generation IV, and Pokemon ruby is a game from Generation III , so you can only get darkrai in Pokemon Platinum, Diamond or Pearl
You dont catch Darkrai in Pokemon Pearl. You can catch it in Pokemon Platinum at level 40.
You have 2 Nintendo DS then send the darkrai (You have to have the mystery gift in diamond or pearl)
darkrai arceas (with plate)
NO