Pokémon Crystal

Legendary Birds

Lugia- lv. 60 Psychic/Flying type found at the Whirl Islands

Ho-Oh- lv. 60 Fire/Flying type found in Tin Tower

TO CATCH LUGIA
1. Get the Silver Wing from the man in Pewter City
2. Surf over to the Whirl Islands and go into the northeast entrance.
3.  Follow the dungeon until you get to a hole in the wall after a waterfall.  Walk in and Lugia should appear in the rear of the room.
4.  Best thing to do is make sure he's asleep.  He knows recover and can make it very frustrating to catch him on low HP.  Water types against him are not a bad idea since he uses Rain Dance and Hydro Pump, but beware of his gust attack.

TO CATCH HO-OH
1. Get the Rainbow Wing from one of the sages after you show Esuine that you caught all the Legendary Dogs.
2. Go to Tin Tower and the power of the wing will send you through a maze-like climb to the roof, where Ho-Oh is.
3.  He is a tough one to capture.  He has Recover, Fire Blast, Sunny Day, and Gust, which should make him a great battler.  My suggestion is to save the master ball for him.
4.  Another reason to get Ho-oh a.s.a.p. is because of it's held item, Sacred Ash, which will save your costs on Revives and Max Revives because it completely revives all of your fainted Pokémon.  Talk about becoming your own walking Pokémon center...