Question

How do hidden powers affect Pokemon battles?

Comments

What do you mean? As far as I know, Hidden Power has nothing to do with how Pokemon battles work.

Answer 1

Hidden Power has no in-battle effects. It's a move whose type varies depending on the odd/even ratio of the user's IVs.

Let oo represent odd and ee represent even.

oo/oo/oo/oo/oo/oo is Hidden Power Dark.
ee/oo/ee/oo/oo/oo is Hidden Power Ice.
oo/ee/ee/ee/oo/oo is Hidden Power Water

Et cetera.

Hidden Power has no in-battle effects other than damage.

Answer 2

If you are talking about the Pokemon move Hidden Power...

Hidden Power is a unique Pokemon move because of it's ability to be any type except Normal and Fairy. This makes it very popular as a "Coverage" move, because it provides Pokemon with an attack type they would not normally have access to, and is usually Super Effective against a type they themselves are weak to. Each individual Pokemon's Hidden Power is of a different type, depending on their Individual Values (IVs). It can often be a pain to obtain a Hidden Power of the type you want for a given Pokemon, but it is always worth it.

If you are talking about Hidden Abilities available to Pokemon.....

Hidden Abilities are not usually obtainable in the wild, requiring use of the Friend Safari, DexNav, etc to obtain. There are also occasionally distribution events of Starter Pokemon that have their Hidden Abilities.