Instructions
Visit Vermillion City and head to the gym to challenge Lt. Surge. Bring Pokemon Level 50 and above, showing preference for rock- and ground-type moves to counter his team of electric-type Pokemon. He fields five Pokemon, ranging in level from 47 to 53. Avoid using flying or water-type Pokemon, which are weak against electric-type attacks.
Head to Saffron City Gym to challenge Sabrina and her team of psychic-type Pokemon. Teach your Pokemon bug, dark or ghost-type moves to counter her team. Leave your ghost- and fighting-type Pokemon on the bench since they'll be weak against her Pokemon's attacks. Her Pokemon range from level 53 to 55.
Walk to Celadon City and visit the gym there to challenge Erika, the grass-type gym leader. Fire-type attacks are your best bet against her team of four Pokemon, whose levels range from 51 to 56. Try not to use water-, ground- or rock-type Pokemon, which are weak against grass-type attacks.
Visit Cerulean City. Misty, the city's gym leader, can be found to the north of town on Route 25. Talk to her there, then return to Cerulean City and head into the gym to challenge her team of water-type Pokemon. Electric- and grass-type moves are great against her team of four, who are between levels 49 and 54. Watch out for her Quagsire, which resists electric attacks with its dual ground and water typing. Remember to search the gym after beating Misty, pressing "A" around the innertubes in her gym to find an item you'll need later called the Machine Part.
Go to the Fuschia City gym to face off against Janine, whose team focuses on poison-type Pokemon. Ground and psychic-type attacks serve you well in this gym, though grass-types should watch out. Make sure to bring plenty of antidotes and full heals in case your Pokemon get poisoned during the battle. Janine's five Pokemon are between levels 44 and 50.
Fly back to Cerulean City, then head east along Route 9. Use the move Surf when you reach the water, and surf down until you find a patch of land. Enter the Power Plant and talk to the man inside to give him the Machine Part you found earlier. Leave the Power Plant and fly to Saffron City, then travel east along Route 8 to reach Lavender Town. Enter the Radio Tower to get the expansion card for your radio. After all of this, you'll be able to wake Snorlax and continue on to Pewter City.
Fly back to Vermillion City and head north toward Diglett's Cave. A wild Snorlax will be blocking the entrance to the cave, so access the radio app on your Poketch and tune it until you find the station playing a lullaby. Snorlax will wake up, at which point you may battle and capture it. After dealing with Snorlax, head through Diglett's Cave. Once you exit the cave you'll finally be in Pewter City.
Visit the Pewter City Gym to challenge Brock, the rock-type gym leader. Rock types have a variety of weaknesses, including water-, grass, ground and steel-type attacks, any of which will serve you nicely against Brock's five-Pokemon team. He has Pokemon at levels 51 through 54.
Head south from Pewter City, passing through Viridian City and Pallet Town. Surf southward from Pallet Town until you reach Cinnabar Island. Head east from here to reach the Seafoam Islands. The fire-type gym leader, Blaine, has moved his gym here because of a volcanic eruption on his home at Cinnabar Island. Use water-type Pokemon to put out his fire, avoiding steel-, rock- and grass-type Pokemon, which will all be weak against his Pokemon's attacks.
Return to Viridian City to challenge Blue. Blue has a well-rounded team of Pokemon with a variety of types, ranging from Level 52 all the way up to Level 60. Electric attacks will be helpful against his Gyarados and Pidgeot, while water types may help when fighting Arcanine and Rhydon. A good psychic-type move will help against Machamp, while fire- or dark-type moves will come in handy against Exeggutor. Make sure you have high-leveled Pokemon for this battle, since his team is particularly hardy.