they live in Donald corcle
Go to the lavender town radio tower and talk to the guy who was pacing. He''ll give you a special feature on your pokegear and then go to the snorlax, go to the tippy-top of the corcle on your radio until you say pokeflute, and then talk to the snorlax. It''ll wake up, and you can catch it. Lv.50.