In addition to the traditional eight Gyms to conquer, the new games introduce a couple of optional "candidate Gyms" who have yet to be officially recognised by the League. They are hidden away in remote, difficult to reach locations (you WILL need HM moves to reach them) and their badges aren't counted as part of the eight required Badges to enter the League.
However, there is an incentive to defeat them: aside from the Gym Leader handing out powerful attack TM's, their Badges will have special in-game effects comparable to the little stat boosts Badges gave you in the early gens. Stuff like winning slightly more prize money, receiving a bit more experience, somewhat raising accuracy or capture rates. What's more, they stack, so items like the Amulet Coin, Lucky Egg and Wide Lens won't be invalidated.
Thoughts?