Instructions
Progress through the game until you have defeated Koga in the Fuchsia City Gym to win HM Surf. You will need this skill to reach the area where Zapdos resides.
Teach Surf to any Pokemon that can learn it, such as most water types. Bring this Pokemon with you.
Level up a team that can fight Zapdos. The legendary bird is level 50 and an electric type, so using ground type Pokemon will make the fight easier. Avoid using water type Pokemon in the fight, so keep the Pokemon used for Surf out of the top slot.
Fly to Cerulean City and follow Route 10 toward Rock Tunnel. From the Pokemon Center at Rock Tunnel, head north to find a small stream.
Surf up the stream, following the path until you reach the Power Plant. Go inside the building and fight your way through the building by following the main path.
Find Zapdos at the very end of the Power Plant, just before the door out. Zapdos waits right along the path to the final exit. Save your game and speak to the bird to begin the fight.
Damage Zapdos until his health falls into the yellow. Because Zapdos is a legendary Pokemon, you will have a harder time catching him than usual. If you can safely drop his health into the red, you will have a better chance. Once you've lowered his health enough, begin throwing Pokeballs until one works. The higher quality ball you use the better your chance of success.