i am fascinated to see how this topic has captured this much attention and has bring this much talking....interesting!
I will summarise: snorlax is not legendary(its just rare, like skarmory).
Lugia on the other hand is a legendary pokemon(according to both the anime and the games).
Its genderless and unbreedable according to the game. But according to the anime it is breedable and so must have gender.