In platinum, no I don't think you can...
but in diamond and pearl you either need an event (for example: go to toys-r-us to get manaphy) to get darkrai or, send it to a friend using Pokemon ranger:shadows of almia
then have them link trade it to you.
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note:a darkrai event might come up soon (for platinum), i dont really know
im pretty sure you can't catch it without cheats, its liek shaymin or acreus
You would have to wait for a new mystery gift to get Darkrai, it's the only way without cheats.
Nope.
Girantina, Heatran, Dialga, Mespirit, Azelf, Uxie, Shaymin, Cresselia and probably Darkrai.
Darkrai can be found at Newmoon Island, but you can't do it without cheats. If you use the walk through everything cheat and you are at Full Moon Island, where you can find Cresselia, you have to walk to the right until you get at Newmoon Island. There you can interact with Darkrai.
you cant i think you can not
You needed a Nintendo Event to get an item to trigger an event to catch him, but this is unlikely to return.
In sapphire you cant catch it without events or cheats:-)
http://www.youtube.com/watch?v=YRKPj4tcybE
Darkrai.
You can't get him without events or cheats. For Darkrai, Manaphy and Arceus you need a event to capture him.
i know how to get nearly every Pokemon without a cheating device. do you know how to get Deoxis on emerald Or is there a way to get Darkrai on diamond without cheats?