Yes, it is in goldenrod city.
Yes, you can through trading with wifi.
Trading from heartgold to soulsilver
You get Darkrai by trading in SoulSilver.
You get it by a wifi event.
By Trading
you cant, you have to go to a public wifi center like books a million or panera bread. there you get free wifi and can connect to the gts
no u cant chat .
its a wifi event.
It's on the second floor of any Pokemon Center.
Sorry you cant, the events over, i missed it too.But you can get arceus from AR(action replay), wifi trading (if you've seen it) or future arceus events (unlikely but maybe)
6.
by using wifi or wireless at a certain place