Natures
Jolly raises Speed by 10% and lowers Sp. Atk by 10%. It is applied at the very end of the formula, after IVs and EVs, so the higher the stat, the more the nature gives and takes.
Speed for a physical attacker. The same rule as Adamant, only the other way around: you hit a little weaker, but earlier.
Flavor
Likes Sweet, dislikes Dry. This matters for Poffins, Pokéblocks and Berries: a Pokémon eats a disliked flavor reluctantly, and healing works worse.