You can get it from an event or trade.
Darkrai.
no sorry its impossible without an action replay
Yes, but you will need the member card.
Get the key from Mystery Gift and open the door in caveport that is locked.
Action Replay or you could never get one without that pass... :-/
this is impossible without cheating, even with cheating it may not be possible.
you need a event which happened a year ago so now its impossible without cheating
you need to go to a Pokemon convetion you know like Pokemon world in New york city
im pretty sure you can't catch it without cheats, its liek shaymin or acreus
Of course, a Master Ball catches any Pokemon without fail, Legendary or not.
Go to youtube and write "Pokemon Diamond and Pearl-HOW TO CATCH DARKRAI-WITHOUT ACTION REPLAY-TWEAKING GLITCH". It works! See for yourself.