HOW TO FIND DARKAI IN POKEMON DIAMOND???

ComicmanxThere are two ways, depending on what you have.If you have the ROM, get an emus that supports action replay DS codes.
If you have the actual cartridge buy the AR DS at a walmart or something.Next, go to action replay homepage, and depending on how you choose:
Mystery gift - Go to the european codes and enter the darkrai mystery gift code.
Go into a pokemart, get the members card, then go to the inn at canalave.
Walk/Run through anything - Go to the island with cresselia then keep walking left (through the water) and you'll reach
another island (the colors might mess up, just access a menu then exit).Then beat catch darkrai. If you mess up, use the rebattle darkrai code and repeat either step, they both work as long as darkrai is back on the island.

there are five more ways.
flashcart with the rom using AR.
flashcart with the rom using Pokesav, editing in member's card via mystery gift panel.
flashcart with the rom using Pokesav, just creating a darkrai.using an emu, using pokesav the two different ways mentioned above.i do have a question for you though. if you already have the member's card then why do you bother to walk through walls and crap. the member's card directs you right to darkrai without having to do that.

if you live in australia you can go to target during the 30th october to 9th november and upload darkrai to you pokemon pearl/diamond

Cresselia is on FullMoon Island... Darkrai is New Moon Island... I'm sure I'm correct.Just pokesav it... nothing special about the particular in-game Darkrai... IV's might suck and you'll prob just pokesav-edit the IV's, EV's, attacks...Shadow

Pokesav would be easiest. If you use AR, you can use the walk through anything cheat, and go right of the Island you find Cresslia. Full Moon island, I think. Also, use a master ball cheat if you are as lazy as me.