Pokémon IVs and EVs

IVs, short for Individual Values, are hidden numbers attached to each of a Pokémon's six stats. Each one ranges from 0 to 31, and a value of 31 is the best a stat can have. Think of them as a small genetic bonus baked into every Pokémon.

IVs are decided the moment you catch or receive a Pokémon, and for wild Pokémon they are usually random. Because each stat has its own IV, two Pokémon of the same species and level can end up with slightly different final stats. The gap is small, but at high levels it adds up.

EVs, short for Effort Values, are hidden points a Pokémon earns by battling. Every Pokémon you defeat gives a small number of EVs in specific stats, and those points gradually raise the matching stat. The more you battle, the more EVs a Pokémon builds up.

There are limits: each stat can hold up to 252 EVs, and a single Pokémon can carry 510 EVs across all its stats combined. That means you cannot max every stat, so EV training is about choosing which two or three stats to pour points into. Unlike IVs, which are fixed, EVs are yours to shape.

Because IVs are hidden, the games give you a tool to read them, often called the Judge function. Once you unlock it, it appears in your Pokémon storage and rates each stat, telling you which are strong and which are weak without showing the exact number. It is the standard way players size up a Pokémon.

How you unlock the Judge function differs from game to game, but in the modern games it becomes available after you make some progress in the story. Once it is on, you can check any Pokémon in your boxes at a glance.

You cannot lower an IV, and you cannot rewrite the underlying number. What you can do, since Generation 7 (2016), is raise a stat's effective value through a feature called Hyper Training. It uses items called Bottle Caps and sets a chosen stat to perform as if its IV were maxed.

The catch is that the hidden IV number itself stays the same; only the stat's in-battle performance is boosted. In practice that is all that matters, so Hyper Training lets you perfect a Pokémon you already have rather than hunting for one with better IVs.