I have a really bad compulsive disorder that usually forces me to do crazy shit, like catch every pokemon i've seen in the wild, but for once it seems to have paid off. I used all of the pokemon in my boxes at the Pc (Currently 5) to test my theory that if a pokemon has 3 abilities to choose from that it will almost never (If not definite) be caught in the wild or by special event, with it's hidden ability. This is excluding hatched pokemon because currently I haven't tested trying to get a hidden ability from a 3 ability pokemon yet. Basically, I tallied up every pokemon in my Pc that had 3 abilities and 2 abilities (Excluding pokemon with only 1 ability and duplicates) and got 33 pokemon that can learn 2 abilities and 83 pokemon that can learn 3 abilities. What I found was that 17/33 of the pokemon that had 2 abilities were caught with their hidden abilities without me resetting any of them, which was including pokemon from special events. Oddly enough that's about a 50/50 chance, so it sounds about right. You'd expect to see a 1/3 chance of getting a hidden ability on a pokemon that has 3 abilities, but out of 83 pokemon that could learn 3, none had their special ability. If anyone has found a pokemon that has 3 abilities with their hidden ability please tell me, but if not, I think this might be why people are finding it difficult to find some pokemon with hidden abilities. I hope this wasn't taken the wrong way, I just wanted this to be brought to attention because i'm sure it's something that was just overlooked on accident and can be corrected in a future update.
Edit: Grammar. Ocd'in it up.