If you're here, you probably just started Pokemon Wifi Battling or learned about something called "EVs". When I first heard the term, I thought it was "Eevee" and shrugged it off. However, this is a very important aspect in winning a battle. EV stands for Effort Values. The "Effort Values" are gained by killing a certain pokemon. For example, if you kill a magikarp, you would get 1 point in speed. To figure out what pokemon gives points in what section (HP, Attack, Defense, Special Attack, Special Defense, Speed) all you have to do is go to the website:
www.pokemondb.net. Search the pokemon, and near the top of the page, the site should say "Ev Yield:" This tells you how many EV a pokemon gives.
So you might be asking how do EVs affect your pokemon. Every 4 EVs you get in a certain stat or section, raises your the stat or section by 1 point. For example, if your pikachu has 83 speed, and you kill 4 magikarps with the pikachu, then your speed will be 84. Now you might be coming up with crazy thoughts such as having a thousand EV in your pokemon. This is not how it works. Every stat can only have 255 EVs in it. However, 252 is the most you should have in the stat because your stat won't go any higher if you put more. Also, you can have 510 EV in total on a pokemon. So on a pikachu, someone might put 252 EV in Attack, 252 EV in speed, and 6 EV in HP. If you put 252 in one stat the stat shud raise by 63 points - AWESOME.
At first EV training seems daunting, but don't worry certain things will help you. POKERUS- the pokemon virus doubles the amount of EVs you get from 1 kill. So if Pikachu had Pokerus, it would get 2 EV in speed instead of 1. Pokerus is attained by chance, but Pokegen can give it to you automatically (a guide for another time). Certain Items also give you more EVs.
Power Weight - adds 4 more HP EVs points to every kill.
Power Bracer - adds 4 more Attack EVs points to every kill.
Power Belt - adds 4 more Defense EVs points to every kill.
Power Lens - adds 4 more Special Attack Evs to every kill.
Power Band - adds 4 more Special Defense Evs to every kill.
Power Anklet - adds 4 more Speed EVs to every kill.
So if we kill a magikarp while the pokemon wears a Power Anklet, Pikachu gets 5 EV points! And if Pokerus is also on Pikachu, you get 10 amazing EV points on Pikachu - WOW! Also know that if you wear Power Lens while killing a magikarp, you get 4 Sp Attack EVs and 1 Speed EV.
Now you know what EV training is, and now you can finally own your friends at Pokemon!