IVs, EVs and Natures: Building the Perfect Competitive Pokémon

A Pokémon's in-game stats are the product of four inputs: base stats (fixed per species), IVs (0–31, rolled at encounter, permanent), EVs (0–252 per stat, earned by training), and nature (±10% on one stat, −10% on another). The base stats set the skeleton; the other three are the knobs every serious player turns. Am I a physical attacker or a special attacker? Slow and bulky, or fast and frail? How much Speed is enough to outrun the current meta? These three systems are how you answer those questions in exact numbers instead of vibes.

Individual Values (IVs) range from 0 to 31 and lock in the moment a Pokémon appears. Each IV point is worth exactly one stat point at level 100, so a 31-IV Attack means 31 more points than a 0-IV copy at the same level — the difference between Garchomp's earthquake cleanly 2HKOing Skarmory and missing the KO entirely. At level 50 the contribution halves, which is why level-50 formats are so sensitive to IVs. Two numbers matter beyond the obvious “max them all”: 0 Attack is prized on special attackers and walls because it minimizes Foul Play and confusion self-damage, and 0 Speedis the linchpin of Trick Room teams (slowest moves first) and maximizes Gyro Ball. Don't chase perfect IVs by the same blind rule — decide which stats you want low long before you breed.

Effort Values (EVs) are the most flexible of the three systems because they are fully under your control. Every defeated Pokémon awards EVs of a specific stat, vitamins and feathers provide them directly, and EV-reducing berries fix mistakes. What matters competitively is the arithmetic: the stat formula divides EVs by 4 (floored) before adding them, so 252 is the most EVs that ever pay off in one stat — running 255 wastes 3 points that do nothing. The shared cap is 510 total, and every build is a budgeting problem spent across that cap. The classic spreads below cover 95% of what you will meet:

A nature multiplies one stat by 1.1 and another by 0.9. That 10% looks small until it lands on the stat where a matchup is decided — a Jolly (+Spd, −SpAtk) Garchomp reaches 333 Speed and outruns Timid base-100 sweepers, flipping a 50/50 into a guaranteed out-and-move. The rule is simple: boost the stat that wins games, hinder the one you never use. Physical sweepers use Adamant/Jolly, special sweepers use Modest/Timid, walls use Bold/Impish/Careful/Calm, and Trick Room builds actively reduce speed (Brave, Quiet). HP is never affected by nature, so it is never hindered. For the full table mapped to roles, see our companion article The Best Nature for Every Battle Role.

From Generation 3 onward every mainline game computes stats the same way. For HP: floor((2 × Base + IV + floor(EV ÷ 4)) × Level ÷ 100) + Level + 10. For the other five stats: floor(floor((2 × Base + IV + floor(EV ÷ 4)) × Level ÷ 100) + 5) × nature. Read it as three stacked steps: first combine the base, IV and EV-derived number; then scale by level and add a flat 5; then apply the nature multiplier. The floors in the middle are why odd EV totals get silently wasted and why nature never produces fractional stats. You can feed these exact numbers into our IV calculator to see the whole formula run live on any build.

Let's build the famous Jolly Garchomp from scratch. Target: a physical attacker that outruns everything below base 110 Speed, survives an Ice Shard, and hits hard enough to take chunks out of bulky walls. Start with base stats — its 130 Attack and 102 Speed are why we bother. Give it 31 IVs everywhere except Special Attack, which we set to 0 (a special move is never used; 0 minimizes confusion and Foul Play chip). Then budget EVs: 252 Speed to ensure the 333 Speed number, 252 Attack for power, 4 in HP for the free level-50 point. Finally a Jolly nature to boost Speed and hinder the unused Special Attack. Feed it to our IV calculator and you get exactly the 333 Speed / 394 Attack spread competitive Garchomp is famous for. Every competitive build is this same four-step process: define the target, set the IVs, budget the EVs, choose the nature.

• Running 255 EVs — beyond 252 is wasted because everything gets floored at the ÷4 step.
• Applying nature to HP — no nature ever touches HP.
• Assuming Hyper Training changes IVs— it makes a stat behave like 31 but the stored IV is unchanged, so a “trained” 0-Attack Pokémon still puzzles breeders.
• Copying a spread you don't understand — a meta Speed tier changes every generation; tune your own EV number instead of trusting a season-old one.

Start with the companion articles in the Academy: Team Building 101 turns this numbers foundation into a six-member plan, and Type Synergy: Defensive Cores shows how to make your bulk actually resist the meta.