You have to use the Pokemon Flute that you get from Lavender town in the radio tower after you complete the powerplant thing.
AnswerOK.If you want the answer for SoulSilver, here it is.
First, Make sure you have given the machine part to the Power Plant Manager.
Then, go to the Lavender Radio Tower and talk to the Director. He will give you
the EXPN Card. Then, go up to Snorlax and Manually tune the radio to the PokeFlute
Station in the middle top section. Then press A and the Snorlax should wake up
and battle you. It's on Lv 50 and is the only one in the game. Catch it.
With the Pokeflute.
Chat with our AI personalities
you'll need the poke flute
The radio will be your instrument to wake up the sleeping Snorlax. There's a certain radio station that plays the poke flute. When you face Snorlax, tune in to that station and let the Snorlax hear the flute for it to wake up.
You have to wake up the Snorlax in front of Diglett's cave and catch him. He is holding leftovers.
There's only one Snorlax in the game, and that is in front of the Diglett Cave. To wake it up, you'll need the Pokeflute playing as your radio channel.
After you get the pokeflute you turn it on and go to the sleeping snorlax and it wall wake up you will be able to fight it at level 50