You can if you trade. . .
Yes,you can get it by trading with d/m,p/r,p/t
Yes you can you rechallenge evry gym leder ( including the kanto ones) at least 5 times and then you goto mr pokemon and he tells you how to get darkrai
You can't get it in heart gold.
Yes you can. All you have to do is battle all the gym leaders a couple of times. Then go to Mr. Pokemon and he tells you how to get Darkrai. :-]
Yeah of course you can!