What are evs?
Effort Values, better known as EVs, are an important part of Pokemon training. EVs will greatly boost your Pokemon's stats and make them stronger in battle. But first, let's see what these EVs actually are.
What are EVs?
EVs are points that you get when you battle and defeat other Pokemon. Every Pokemon gives a certain amount of EVs for each of the six stats - HP, Attack, Defense, Speed, Sp. Attack, and Sp. Defense. For instance, defeating a Starly will give you 1 EV in your Speed stat. Defeating a Machop will give you 1 EV in your Attack stat.
Every 4 EVs is equal to one stat point (the numbers that show up on your Pokemon's stat screen in your game). So defeating 4 Starlys will raise your Speed stat by 1 point.
Each stat can have a maximum of 255 EVs before it cannot be raised anymore. And you can't have more than 510 EVs total for all of your stats.
But wait! If 4 EVs equal one stat point, then 255 and 510 aren't divisible by 4!
That's right. If you put 252 EVs into one stat, you will have 3 EVs left over since 255 - 252 = 3. Those 3 EVs won't help that stat anymore since you need 4 EVs to raise 1 stat point.
Since 510 is the double of 255, that means you will have 6 EVs leftovers since 6 is the double of 3. You can take 4 EVs from those leftover 6 to raise another stat by 1 point.
After that, you'll still have 2 extra EVs left. You can ignore them because those 2 EVs don't mean anything. That means once you have 508 EVs, you are done with your EV training.
Now that you know the math, you can see why EVs are so important. Since each stat point is worth 4 EVs, 508 EVs divided by 4 is 126. That means a fully EV-trained Pokemon will have 126 more stat points than one with no EVs. That's a huge difference!
I battled 40 Starlys for 40 Speed EVs, but my Pokemon's Speed only went up by 3! Should it have gone up by 10?
Don't worry if your stat doesn't increase by the exact number of EVs you put in. A Pokemon's stats increase gradually, especially low level Pokemon. So don't worry if your Lv. 10 Pokemon's stat only increased a little even though it gained a lot of EVs in that stat. Once it reaches Lv. 100, you should see the full results.
How do I keep track of my Pokemon's EVs?
You'll have to find your own way since the game doesn't tell you how much EVs you have. Either write them down on a piece of paper or keep track of them in a word document or spreadsheet on your computer. Everytime you fight an opponent Pokemon, find out how much and what kind of EVs it gives and record them.
When is the best time to start EV-training?
Your Pokemon gain EVs as soon as it gains experience by battling other Pokemon. But if you haven't been keeping track of your EVs, it can be very hard to know where those EVs went. So for your convienience, the best time to start EV-training a Pokemon is immediately after you catch or hatch that Pokemon. Wild Pokemon have no EVs at all, even if they were caught at a high level. The same goes for Pokemon that just hatched out of their eggs. So you have a clean slate from which to start EV-training.
Items that effect EVs
Vitamins (HP UP, Protein, Iron, Calcium, Carbos, Zinc)
Everytime you use one of these items, your Pokemon gains 10 EVs in that particular stat it raised. A Pokemon can only have 10 of each Vitamin, meaning it can only gain 100 EVs in each stat from Vitamins. Still, that helps a lot, because 100 subtracted from the total 252 is 152. You'll only need 152 EVs before you are done training that stat.
This is a very important item for EV training. The Macho Brace is a hold item that cuts the user's Speed in half, but it doubles the EVs you gain from each opponent you defeat. That means instead of fighting 252 Starlys to get 252 EVs for your Speed, you will only need to fight 126 Starlys to get the same amount when holding the Macho Brace.
Power Items add 4 EVs to one of your stats after defeating each opponent, along with the EVs you normally gain from the opponent. For instance, defeating a Starly with a Power Weight gives you 1 Speed EV from the Starly and 4 HP EVs from the item. Defeating a Starly with a Power Anklet gives you 5 Speed EVs, 1 from the Starly and 4 from the item. Power Items are only available from the Battle Tower/Battle Frontier for 16 BP each.
Power Weight: +4 HP EVs
Power Bracer: +4 Attack EVs
Power Belt: +4 Defense EVs
Power Lens: +4 Special Attack EVs
Power Band: +4 Special Defense EVs
Power Anklet: +4 Speed EVs
Not only does the EXP. Share give EXP to the user holding it, it also gives EVs to the user. The user doesn't even have to be in battle to get this. This is a good way to train low level Pokemon in both EXP and EVs.
In the Emerald version as well as the 4th Generation, certain berries will decrease a Pokemon's EVs. This can be useful if you've trained a Pokemon to a high level, but didn't pay attention to the EVs. By feeding them enough of these Berries, their EVs will be erased and you can start EV-training them properly.
Pomeg Berry: -10 HP EVs
Kelpsy Berry: -10 Attack EVs
Qualot Berry: -10 Defense EVs
Hondew Berry: -10 Sp. Attack EVs
Grepa Berry: -10 Sp. Defense EVs
Tamato Berry: -10 Speed EVs
The PokeRus isn't an item, it's a rare disease that your Pokemon has a chance of getting. PokeRus doesn't have any other effect besides doubling the EVs you gain after each opponent you defeat. It can be combined with the Macho Brace so that you can gain EVs 4 times quicker. So instead of fighting 252 Zigzagoons to get 252 EVs for your Speed, you will only need to fight 63 to get the same amount when having both the Macho Brace and PokeRus. But getting PokeRus is rare and completely random, so don't count on it.
EV-Training Hot Spots
In each game, there are certain areas where the wild Pokemon give only one kind of EV. This is very helpful during EV-training since you don't have to runaway from any Pokemon that don't give the EVs you are looking for
How to ev train
Find a place where your Pokémon can battle another Pokémon who is on a higher battle level than your Pokémon. The stronger the Pokémon you battle, the more points you earn.
Battle and win against another Pocono and receive 1 to 3 points. These points are Effort Points, EPs, not EVs. The kinds of EPs you earn depend on the type of Pokémon you have. If you have an attack type, you earn Attack EPs. Special attack Pokémon get Special Attack EPs.
Collect points until your Pokémon has 510 EVs, the maximum number a Pokémon can collect. For every 4 EV points you earn and put into a stat, that stat will grow by 1 point when it comes time to Level Up. Each Pokémon, if trained to its maximum potential, can earn up to 127 extra points.
Give your Pokémon vitamins. Don't load up too much of one vitamin, as you can only use 10 of each kind. For example, if you use 10 of your Calciums, your Pokémon will collect 100 EV points.
Use EV points to boost your stats up several levels. You must keep track of the points your Pokémon wins since they are not always visible.
Pay attention to the screen after you are done battling to learn how many points you and your Pokémon have earned. A window will pop up and tells you how many and what kind of points you earned.