How do you get vaporeon in Pokemon LeafGreen?

Well, you can't get it by a wild Pokemon or an egg. You have to find an Eevee. To

get Eevee, you need to go to Celadon City. When you get there, go right up the

little path until you find a patch of dirt. Walk into it, then get to the top by climbing

up all the stairs until you reach the top. When you get to the top, talk to the guy in

the little building on top, and there will be a PokeBall sitting on the table. Pick it

up, and you now have an Eevee. To get Vaporeon, go to the Department Store in

Celadon City, and buy a Water Stone and then give it to Eevee.

Hope this helped :)