I was wondering if Lugia was available in HG without trading?
Yes it is, go to the Whirl Islands after the Elite 4 and It Will Be There, But there wont be a ceremony. its at lvl 70.
EDIT: Also What Trachy Said, A Guy In Pewter City Will Give You A Silver Wing ;)
Yep, a guy in Pewter City gives you an item called the Silver Wing which allows you to get Lugia.
Yes, you can obtain it at Whirl Island. It's at lv70 with Aeroblast, Punishment, AncientPower, and Safeguard...