Effort Values (abbreviated as EVs for short), also referred to as base points in-game (not to be confused with Base Stats, which are completely different), are an important part of Pokémon’s calculated stats. Each of an individual Pokémon’s six stats have an Effort Value associated with it, ranging from 0 to 252 (or 255 in Generation III–V), and Pokémon have a maximum of 510 EVs across all six of their stats.
Effort Values were introduced in Pokémon Ruby and Sapphire and have been present in every main series Pokémon game, with the exception of Let’s Go Pikachu and Eevee, since then; prior to Generation III, there was a somewhat similar system known as Stat Experience, although it had no such cap across all stats, meaning any Pokémon could max out all of its stats instead of picking specific stats to focus on.
Effort Values are gained whenever a Pokémon gains Experience Points, and each Pokémon species has a predefined yield—known as the EV Yield or Effort Value Yield—that determines the EVs a Pokémon gains when it is knocked out. Unlike Experience Points, Effort Value Yields are not split or divided amongst the party—each participating Pokémon receives the full amount. All Pokémon have an EV Yield of 1 to 3 points spread across the six stats, with evolved Pokémon typically granting more EVs than unevolved Pokémon.
Effects of Effort Values
The main purpose of Effort Values is to provide a bonus to a Pokémon’s stats. At level 100, assuming the Pokémon has a neutral Nature (no positive or negative effect to its stats), every 4 EVs equals 1 actual stat point. So, for instance, a Pokémon at level 100 with 252 Attack EVs will have a total of +63 Attack compared to a Pokémon with 0 Attack EVs.
This number is always rounded down, which is why the cap was lowered from 255 to 252—both would result in the same increase of +63 at level 100, so the extra 3 points into it would be wasted.
The bonus to a Pokémon’s stats is proportionate to its level, so it isn’t that when a Pokémon reaches level 100 it instantly gains +63 if it has maxed out EVs in a stat—instead, it is part of the stat calculation formula, so at level 50 it is approximately half as much of a bonus as it is at level 100 (although it is always rounded down, so the same “EV spread” might not be as optimal at lower levels). In other words, it doesn’t matter whether a Pokémon is level 25 or level 100—EVs will increase its stats accordingly and it will be proportionate to that level, more or less.
EV Training
In order to optimize a Pokémon’s stats, all competitive players and many casual players engage in a process commonly referred to as EV Training. This is the art of fighting against specific Pokémon to raise their Pokémon’s EVs in a specific way, such as 252 Attack EVs, 252 Speed EVs, and then 6 HP EVs as an example. This maximizes the Pokémon’s offensive capabilities and its speed, giving it an edge compared to Pokémon that haven’t undergone EV Training.
There’s a full EV Training Guide on the Marriland website that outlines this process in more detail, and it covers how to EV Train in every single Pokémon game where it is available in.
Ways to Speed Up EV Training
While the EV Training Guide lists all of the methods to increase the amount of EVs gained and thus speed up the process, here is a quick summary of the different methods that improve the yields you earn:
Macho Brace
A held item introduced in Ruby and Sapphire, the Macho Brace, when held, doubles the amount of EVs a Pokémon gains from battles (but not vitamins or other methods). It halves the Pokémon’s Speed stat while it’s held, but only during battle and has no impact on its growth, despite what the in-game descriptions say.
Pokérus
The Pokérus is a super rare “virus” that is, thankfully, completely beneficial to your Pokémon instead of being a bad thing. It causes the Pokémon with the Pokérus, regardless of whether or not it is currently contagious, to always receive double the amount of EVs it would normally gain from battles (but not vitamins or other methods). This bonus is applied after other bonuses, making it particulary effective when paired with the Power Items (shown below).
“Power Items”
Introduced in Diamond and Pearl, the set of six “Power Items”—the Power Weight, Power Bracer, Power Belt, Power Lens, Power Band, and Power Anklet—grant a +4 bonus to the EVs earned for their respective stat, and this is applied before the Pokérus bonus, meaning you can gain +10 EVs per fight by fighting something that gives just 1 EV if you have the matching Power Item and the Pokérus, speeding up the process substantially.
Vitamins
The vitamin items are quite expensive, but they raise a Pokémon’s EVs for the respective stat by +10 per vitamin. However, prior to Pokémon Sword and Shield, these items “have no effect” when used on Pokémon that have 100 EVs or more in that stat (starting in Generation VIII, they can be used freely all the way up to the maximum).