Lugia cannot be caught in Pokemon Diamond/Pearl/Platinum. You can trade for one from HeartGold/SoulSilver or migrate one from a GBA Pokemon game via the Pal Park.
You can't catch a Lugia anywhere in Pokemon Diamond.
You can't catch Lugia in Pokemon Diamond. You can only get it through trading or cheating.
you cant get Lugia in Pokemon Diamond
You must trade to get Lugia.
Dark Lugia is also known as Shadow Lugia. You can get it in the game Pokemon XD and it is possible to trade it over to Diamond version.
It is not possible to get a Lugia egg in Pokemon Diamond. It is generally impossible to get an egg of a Legendary Pokemon the only exceptions being Manaphy and Phione.
you cant you have to migrate it from Pokemon firered/leafgreen
A person that has SoulSilver
== == No
You have to trade it from somewhere else.
There is no Action Replay code in order to get Shadow Lugia in Pokémon Diamond, Pearl, or Platinum at the moment.
Sorry mate. No such thing as dark lugia