Depends on the game usually you have to receive it from somewhere in the game. For example lets say you have diamond somewhere in the game a person gives it to you, or Pokemon silver Bill gives it to you in goldenrod city.
there is no eevee :(
You can get an Eevee from Bill in Goldenrod city.
You can find eevee in Celadon City in Kanto as a Game Corner prize.
No, it isn't possible to find Eevee in Sapphire. You'll have to trade one from FireRed/LeafGreen.
The only place to find an Eevee is at Bill's house or maybe at the GTS.
You can not, you have to go to bill's house in goldenrod city to get a eevee.
As far as I know, you can only breed an Eevee with a Ditto, as I myself have been unable to find a wild Eevee. You can find a Ditto (which has no gender) after you beat the Elite Four.
You can find it from the Trophy Garden.
There isn't an eevee in Pokemon Emerald. If you go to serebii.net you can find lots of other way to get eevee in the other games
You can't find Eevee in Pokemon Ruby, but you can trade for it from Fire Red, Leaf Green, and XD.
Eevee is rather tricky to recruit, but you can find them in Joyous Tower floors 12 to 17.
you can find it at VOLCANO CAVE in BOYLELAND