Hi guys, HeartGold24(SoulSilver42) here to help you rookies that are getting into EV training in B/W, I will post a guide for DPPt,HGSS if there is high demand for it.
There's nothing horrendously complicated by EV training, and nor is it anywhere near as time-draining as it used to be.
Note: In previous games, being granted a ribbon by a woman who'd look at your Pokemon would tell you that the EVs are maxed out. It works slightly different in Black and White. In Opelucid City there's a woman in one of the houses that will tell you something on the lines of “put a lot of effort in” when a Pokemon is fully EV trained but won't grant you a ribbon.
Helpful Items
The Power items are the way to go if you want to train quickly, and there's little worry in using them. However, you won't be able to send them over them from a 4th gen game as you expect, instead you'll have to earn them in the Battle Subway. You can do it without the items but its very, very tedious.
The items themselves had 4 stat points every battle depending on what stat the enchant. For example, if holding a Power Bracer to a Pokemon (nd then defeating an enemy Patrat (1 Attack EV), the result will look something like this.
Patrat's attack EV (1) + Power Bracer yield (4) = 5 Attack EVs.
Of course, Pokerus doubles this giving you 10 Attack EVS. Not bad for one battle eh. Remember, a Power Item will give you its corresponding EV regardless of what EV you receive from Battle. You could equip a Power Bracer and attack nothing but Special Attack Giving EV Pokemon and receive 1 Special Attack EV and 4 Attack ones from a single battle.
Here are the Power Items and the stats they raise.
Power Item EV
Power Anklet 4 Speed
Power Band 4 Spec. Defence
Power Belt 4 Defence
Power Bracer 4 Attack
Power Lens 4 Spec. Attack
Power Weight 4 HP
In addition to that, new items called Wings are available and raise a Pokemon's EV total by 1. What's the point you may say? Well, for one, they're not subjected to the cap that vitamins have, so in theory you could give your Pokemon 252 in special attack, and two, they're the only way to EV training level 100 Pokemon (such as the ones you get in events.)
They are found at Driftveil Draw Bridge and Marvelous Bridge in the shadows that randomly appear.
Wing EV
Health Wing 1 HP
Resist Wing 1 Defence
Clever Wing 1 Spec. Defence
Muscle Wing 1 Attack
Genius Wing 1 Spec. Attack
Swift Wing 1 Speed
EV Hotspots
Now you have your items, its time to EV train. There are locations within the game that are ideal because of the Pokemon found there, the encounter rate, and so, here they are.
Attack
Route 1 (Unova)
Pokemon EV Given Encounter Rate
Patrat 1 Attack 50%
Lillipup 1 Attack 50%
Attack is easily given with these two on the first route in the game, ideal from training a Pokemon straight from an egg, you'll find nothing but these outside rare shaking grass.
Defence
Pinwheel Forest Inside
Pokemon EV Given Encounter Rate
Sewaddle 1 Defence 35%
Venipede 1 Defence 20%
Either one should appear enough to give you an easy stream of Defence EVs.
Special Attack
Celestial Tower 2F
Pokemon EV Given Encounter Rate
Litwick 1 Special Attack 100%
On the second floor you'll find nothing but Litwicks, and nothing but Special Attack EVs.
Special Defence
Route 4 (Unova), Route 17 (Unova) and Route 18 (Unova)
Pokemon EV Given Encounter Rate
Frillish 1 Special Defence 100%
Found surfing at the above location, Frillish being the only thing found like this will give you out special defence EVs easy.
HP
Route 8 (Unova), Icirrus City and Moor of Icirrus
Pokemon EV Given Encounter Rate
Stunfisk 2 HP 100%
Again, by surfing in these areas you'll always run into Stunfisk.
Speed
Lots of Areas including: Route 1 (Unova), Route 3 (Unova) and Route 6 (Unova)
Pokemon EV Given Encounter Rate
Basculin 2 Speed 100%
at most areas.
Basculin can be found in a lot of places by surfing and the above locations are just example where it can be found 100%.