Where do u Catch Eevee???!!!?

No you can't you have to get it from a person in hearthome city next 2 the contest hall

You can find Eevee in the grassy area behind the Trophy Garden below Hearthome City. When you go inside the Trophy Garden building, go inside the door in the right, where you see a woman standing to the right of the door. Talk to the owner of the Trophy Garden. This is where one of those daily events take place. The Trophy Garden owner will tell you that he saw a certain Pokemon back in the grassy area. Eevee is one of those Pokemon that he can say. If and when he says he found an Eevee back there, now's your chance to go catch one. There is one other way to get Eevee. In Hearthome City, go inside the building that's right next to the Pokemon Center. There you will meet a girl named Bebe. After you beat the Elite Four, and get the National Pokedex, she will give you an Eevee. To recieve it, you must have one empty space in your party.

Hope this helps,
Sk8rboy

There is only one other way than what the above two said, Catch one in any previous game and migrate it up. Hey, it's Still in the Wild.

First beat the elite 4,then get the national pokedex,after that fly to hearthome city and talk to bebe.

Go to the Pokemansion And you find a eevee in A patch under the tree.

You can't in wild.