There are 25 natures but only 20 are good. Neutral natures like Docile and Hardy are bad and should never be used.

For Physical Attackers you want either Adamant (+Atk) or Jolly (+speed) as they boost their defining stats.

For Special Attackers it’s Modest (+SpA) or Timid (+Speed)

For defensive physical Pokémon you want either Impish (+Def) or Careful (+SPDef)

For defensive Special Pokemon it’s Bold (+Def) or Calm (+SPDef)

When in doubt of which to choose between attack and speed boost natures going for, speed is usually the better option as speed is everything lol.

For Slow Pokémon that you want to try Trick Room with always go with a nature that reduces speed. (Brave, Relaxed, Quiet and Sassy) Note! Brave only for physical Pokémon and Quiet only for Special Pokémon.

The last natures (Lonely, Rash, Hasty and Naive are for Pokémon that use both physical and special attacks. This is so you don’t lower either attack or speed stat whilst getting the boost benefit.

Side note I realise thanks to some help Lax and Quiet natures are pretty bad for mixed as they don’t boost either attack or speed and you don’t really have mixed defensive mons for obvious reasons (def lowering effects of these natures)