In crystal there are a lot of legendary Pokemon. Lugia and ho-oh are in the whirl islands and that tower guarded by bald men in ecruteak (not the burned tower) they are at lv. 45 and 70, based on...
well that's easy... it is Latios its a legendary easy to catch but it always flees so nearly impossible. if you have a Pokemon that prevents Latios to flee then your odds of catching it increase...