Elementary, my dear Ledyba.

Pokémon Natures Table

In the later generations, a system of Pokémon Natures was implemented into the games. Natures decide a small variation in the stats of Pokémon. For instance, a Pokémon with an Adamant nature will have slightly more attack and slightly less Special Attack than a Pokémon with a neutral nature, such as Hardy. Natures will also determine what kind of Pokéblock your Pokémon will like or dislike.

Nature Helpful (+10% Stats) Harmful (-10% Stats) Likes Dislikes
Adamant Attack Special Attack Spicy Dry
Bashful ---- ---- ---- ----
Bold Defense Attack Sour Spicy
Brave Attack Speed Spicy Sweet
Calm Special Defense Attack Bitter Spicy
Careful Special Defense Special Attack Bitter Dry
Docile ---- ---- ---- ----
Gentle Special Defense Defense Bitter Sour
Hardy ---- ---- ---- ----
Hasty Speed Defense Sweet Sour
Impish Defense Special Attack Sour Dry
Jolly Speed Special Attack Sweet Dry
Lax Defense Special Defense Sour Bitter
Lonely Attack Defense Spicy Sour
Mild Special Attack Defense Dry Sour
Modest Special Attack Attack Dry Spicy
Naive Speed Special Defense Sweet Bitter
Naughty Attack Special Defense Spicy Bitter
Quiet Special Attack Speed Dry Sweet
Quirky ---- ---- ---- ----
Rash Special Attack Special Defense Dry Bitter
Relaxed Defense Speed Sour Sweet
Sassy Special Defense Speed Bitter Sweet
Serious ---- ---- ---- ----
Timid Speed Attack Sweet Spicy