I envy those who understand EVs and IVs and EV training -__- I used to just capture cool pokemon and make them 10 levels higher to win. I am by no means a competitor lawl xD
EVs are actually quite simple :D
Every Pokemon you encounter in a regular battle offers all Pokes a certain amount of "effort values" when you down them. For example a wild Magikarp encounter offers 1 Speed EV to every Poke that was in the fight.
EVs show up on Pokes in 1, 2 and 3 values which is generally correlated to the evolution position of the Poke. For example, Abra gives 1 Sp.Atk EV, Kadabra gives 2, and Alakazam gives 3.
Now comes for a more confusing part. Keep up! For every 4 EVs you get in one stat you gain ONE stat point. So that means 4 HP EVs = 1 extra HP. Now, keep listening, we're almost done. The most EVs you
should ever get in any stat are 252. That means you can get 63 extra stats in one area (252/4=63), then you can get 64 more in other areas. This is because the maximum number of total EVs any Poke can get are 510, but 508 is the maximum countable number (508/4=127) So that means you can have 63 extra stat points in 2 areas and then 1 extra stat point somewhere else.
What does this all mean? It's easy! Get out a counter and go fight the same Pokemon over and over again. Going with the earlier example, say with Magikarp, once you've fought 252 Magikarp with one Poke, you'll have gained 63 Speed stats! Neat, huh?
Sometimes people divide them up though, you don't have to just max two areas. But on sweepers (big damage dealers) and what not, people like 252 EVs in one stat like Atk or Sp.Atk. :D
Finally, it's important to note these only apply themselves basically when you level up. The EVs apply themselves on each level-up, which is why you sometimes see +6 to a single stat when you have been battling a lot of the same Pokemon in the wild. I know you've seen that before! At level 100 it works a little differently, but you get the basic idea. (:
Also, hello to the OP, and welcome o/