Where is Eevee in firered or leafgreen?

Answer 1

When in Celadon City, go up the right side of the Pokemon Center. Follow the path all the way until you get to the back of a building which has a big door and enter. Once you are in there, go up all the stairs until you reach the top level. There, you will find a door with a sign posted on it saying "I know everything." Go in the door, and once inside you will see an item on a table, walk up and pick the item up. Surprise! It's a Poke Ball with Eevee in it! If you would like an Eevee of a specific gender, just save before you pick the ball up. If you don't get the correct gender, just reload your game and try again.
you can get an eevee in leaf green version. go to celadon city. you must have a Pokemon that knows the HM01 cut to get it. go up in behind the mansion and keep going up the stairs until you get to a room with a sign that says I KNOW EVERYTHING. there will be a pokeball on the table and inside it will be an eevee.

if you want a female, youll luck out. theres only a 12.5% chance youll get one