>>97459611Stats are calculated based on 3 factors
>IV>EV>NatureIVs are innate, you have items in current games to influence them but generally these are decided at birth and you need to breed a shit ton to get mons with max {31} ivs.
EVs is effort value you gain from defeating pokemons, every mon has a specific ev it gives on being defeated and you can have max 252 evs on a single stat and 510 in total.
Nature debuffs one stat and buffs another, for eg "Adamant" gives you +Attack on base stat but decreases SpAtk so this nature is good to have on a physical attacker.