Nature is a characteristic that boosts one stat by 10% and lowers another by 10%. For example, an Adamant Nature boosts Attack and lowers Special Attack. Individual Values (IVs) are hidden values (0-31) for each stat, determined when a Pokémon is encountered or hatched. While you can't change IVs, understanding Natures can help you choose which Pokémon to train. For casual play, Natures are less critical, but for competitive battles, they are essential for maximizing potential.
While Pokemon FireRed and LeafGreen require permanent stat optimization through Natures and IVs, Pokemon Unite utilizes a more flexible system of upgradable Held Items to influence combat performance.
While FireRed and LeafGreen offer limited ways to influence these hidden stats, Pokémon Omega Ruby and Alpha Sapphire introduced more accessible methods for players to track and optimize them.