>>14633029IVs matter, most notably in Speed, as it determines who is the faster of two of the same base speed.
IV breeding is quite easy in Gen VI though, as the Friend Safari Pokémon all have at least 2 perfect IVs.
Refer to some Gen V breeding guide on how to pass them on through breeding, it works the same in Gen VI. Just catch Pokémon in the Friend Safari and chain breed the IVs you desire via egg groups, take a look at those on Bulbapedia or something.
It's piss easy to get 2 perfect IVs, and rather easy to get 3, that's the max that can be inherited. For offensive types you'd usually want HP, primary attack stat, Speed.
