Ability Boosts, Cuts, and Damage!

Question

How much does the ability:

Intimidate reduce attack?

Rivalry boost attack?

Thick Fat reduce Fire and Ice damage?

Rough Skin damage the opponent?

Answer 1

Intimidate lowers attack one stage.

Rivalry boosts the base power of an attack by 25%, (when attacking foe of the same gender), and does 25% less damage when attacking a foe of the opposite gender. It's unaltered against genderless pokemon.

Thick fat reduces the damage by 50%.

a pokemon hit with rough skin loses 6.25% of its HP (1/16).