The Snorlax in front of digletts cave.
So, I have answered the about same question for so many members now, so now I write it here:
1. First you need to have get the power plant working again.
2. Now, go to lavender town's radio tower and speak to the man in brown.
3. He will give you the EXPN Card, witch lets you tune in on different radio channels.
4. Go to the snorlax and open the pokegear and choose the radio.
5. Move the dot to the almost top of the circel until it stand pokeflute.
6. Speak to snorlax.
7. Catch/defeat/run from snorlax to get him away. (It's a really good idea to save in front of him and try to catch him witch heavy ball because it's one of the few ways to get snorlax in the 4th generation games.)
Added by: PokeJan , ID#13955