How much power is added to the punching moves when using Iron Fist?

Question

When Golurk with iron fist uses a punching move how much power is increased, and how to calculate it with 255 EVs in physical attack and other EVs in speed?

Answer 1

It increases the power by 20%. EVs don't effect the ability's power; it effects the Pokemon's stat.
http://bulbapedia.bulbagarden.net/wiki/Iron_Fist

Comments

Its 20%