Whenever battle experience is gained, a Pokémon will gain full EVs from that particular enemy, regardless of if the XP was shared. However, EV-boosting items like the Macho Brace only boost EV gain for the holder.
Also: to give your Pokémon maximum stats, it should start off infected with Pokérus (PKRS).
Sorry to reiterate what others have been saying... Hmm, another way, I suppose, is to just go through Route 1/29/101/201/1, facing what ever little Pokemon you find. Then, when you have the berries, use the Stat-Reducing Berries, which remove EVs to gain Happiness, to wipe the 'slate' clean. That way, you can start off fresh training-wise. Of course, this will be a pain if you're playing Black and White, unless you were lucky enough to get such Berries from the Dream World, eh?
Happy Training.
Whoa bro, better slow down bro, don't wanna be a bro, bro.