Requires:
*A Lvl. 18 MALE Lopunny or Cleffa/Clefairy/Clefable with the ability Cute Charm.[/color]
*Any kind of repel. (Max Repel suggested)
*A pokemon with the skills Dragon Rage/False Swipes and a status changer.

Optional:

Smoke Ball (Route 210 under the 2nd bridge, guarded by Ninja Boy Nathan)

Have to have the National Dex to encounter Eevee in the Trophy Garden.

1. Go to the Trophy Garden located on route 212.
2. Head to the owner's office and save infront of him.
3. Chat with the owner and see if he says he has seen an Eevee. If not soft reset till he does.
4. Make your way to the garden and have your Lopunny or Cleffa/Clefairy/Clefable in the 1st slot.
5. Put on the repel then run/cycle through the grass till you encounter Eevee. There is a 66.7% chance that it will be female! YAY~ =D

An interesting revelation to be sure; however it doesn't need to be either a Lopunny or Clefable; any Pokemon with Cute Charm will make you encounter Pokemon of the opposite gender a lot more often (yes, two-thirds chance). So if you have a male one of those...go for it.

Although, the best thing to do is to make sure that there are Eevees in the garden first.

So ANY pokemon with cute charm? Like Pachirisu or Pichu?
That helped me a lot because you would not believe how hard it is to catch a Buneary.

Pachirisu and Pichu do not get Cute Charm.