Things You'll Need
Instructions
Travel to Johto. You must first finish all the battles in the Kanto region in order to travel to Johto. The first time you visit Johto, you will travel there via the Fast Ship S.S. Aqua in Olivine City. It will take you to Vermilion City and docks once you have solved all the puzzles aboard the ship.
Work your way to Route 21 by battling Gym Leaders in each city. You will need the Surf ability in order to travel to Cinnabar Island. Heal your Pokémon at the Pokémon Center. A sign out front will tell you the gym has relocated to the Seafoam Islands. You will run into Blue, the Viridian Gym Leader, who will ask to see your badges. Once you have defeated Blaine, Blue will offer you a battle at the Viridian Gym.
Use Surf to reach the Seafoam Islands by taking Route 20 east. There will be a number of trainers you will have to battle. If you need to heal your Pokémon and don't have medicines in your bag, travel back to Cinnabar and heal your Pokémon. Blaine only has three Pokémon, but they are tough fighters and can do a lot of damage -- especially his Rapidash.
Find the sandbar at the end of Route 20 and enter it through the eastern entrance. You will need to travel toward the top of the islands to find the relocated Cinnabar Gym and Blaine.
Battle the five trainers to reach Blaine.
Use Surf or Earthquake to take down Blaine's Magcargo. Magcargo knows both Sunny Day and Overheat, which will make it harder on any water-type Pokémon you are using to defeat him and do extra damage to any Pokémon you are using in battle. Magcargo also has a White Herb, which will restore his stats back to normal if he is able to use it.
Use Surf or Earthquake again to take down Magmar as quickly as possible. Like Magcargo, Magmar knows Overheat and Sunny Day, but he also knows Thunder Punch, which is devastating to water-type Pokémon.
Use strong water-type, ground-type or a combination of both types of Pokémon to defeat Blaine's Rapidash. Rapidash is Blaine's prized Pokémon and is much stronger than the other two. Rapidash also knows Overheat and has a White Herb to restore his stats. Another strong fire move that Rapidash has is Fire Blitz, which will do a lot of damage to any Pokémon you are using, especially if either Magmar or Magcargo were able to use Sunny Day.