I want to get an Eevee and I have Pokemon White2 and I need to get one!
There are 3 ways to catch / obtain an Eevee ingame:
You go to the tall grass in the garden area connected to the castelia sewers. It is very rare to find eevee there so good luck. The steps are at the end of the sewer
you can get one from fennel's place in castelia city or find one in the grass though its a 5 percent chance to appear in the castelia garden
Go to the Castellia Gardens that you get through from the Sewers, they are very rare and can take some time to find.