you have to restore power to the Power Plant. And you do that by Battling the Team Rocket member on Cerulean Bridge, and then finding the machine part in the water of the Gym, and returning it to the manager of the Power Plant. Once thats done talk to the manager of the Radio tower. He'll give you the Kanto Radio Card. Tune into the pokeflute and place the radio by the Snorlax.
The Digletts cave is east from vermilion in kanto. like the others said, get a radio card from the kanto radio tower in Lavender town, then tune into pokeflute on your radio infront of the snorlax at digletts cave. then press A on it and itll wake up. its lvl 50 so if you want to catch it get around 40 ultra balls just in case and save infront of it. then you go through the cave and come out near pewter city, where you can battle brock, who has rock pokemon. and while your there you can get silver wing from an old guy standing around, which allows you to find lugia. then go south to pallet town.
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