Catch Zapdos in Pokémon Yellow

You can only catch Zapdos in Pokémon Yellow version once you already have a Pokémon that knows surf.

Steps

Go to Cerulean City. Go East towards the entrance of the Rock Tunnel or from Lavender Town, go north and enter the Rock Tunnel, and go out. You should be able to see the Pokémon Center outside Rock Tunnel.
Use the Pokémon Center as your point. Walk North, surf East, and South until you see a grassy area on your left side.
- If you walk to the west, you will see the old Power Plant.
Enter the power plant. You will be able to pickup several Items and battle Magneton, Magnemite, Pikachu, Raichu, and Voltorb. Go to the west part of the Power Plant (Power Plant is a Maze) and you will see a bird waiting for YOU!

Zapdos is very hard to catch so you need to save the game before trying to catch it. Put it in minimum HP and status should be asleep. Be sure to bring a lot of Pokeballs or Master Ball(s) if you have any.