Tips on how to make breeding easier! If this is what you mean.
First of all, breeding natures. If you give a Pokemon an everstone whilst in the day-care, the will be a 100% chance of the offspring having the same nature in X and Y (in previous Generations it was a 50% chance). So if you have a female Trevenant and male Pokemon in the same egg group with the right nature, give the male an everstone, put them in the Day-care, and the baby Phantump will have your wanted nature!
These are the Pokemon in Trevenants egg group:
And of course how to get multiple everstones, if they were accidentley sold:
Now the abilities. If the Pokemon already has a hidden ability in the day-care, then there will be a 33% chance that that is what the off-springs ability will be, there is no definate way to ensure the right ability, but about 1/3 isn't bad.
If the Pokemon in the Day-Care has a normal ability (like natural cure) there is no chance at all that the off-spring will have the hidden ability, and in Trevenant's case there will be a 50% chance that the offspring will have will have natural cure, and a 50% chance of it having frisk.
A you said, Pokemon in hordes hve a slight chance that Pokemon will be caught with there hidden ability, but if you bring along a Pokemon with sweet scent then when used out of battle you will encounter a horde 100% of the time, if you can find hordes there.
Just as an extra, IV breeding. if the Pokemon in the Day-Care is holding a Destiny Knot, then the off-spring will have 5 random IV stats carried down to the off-spring from it's parents. Pokemon found in the Friend Safari have 2 perfect IV stats, but I know you don't have that option. Also, a power item (when given to the Pokemon in the day-care) will garrentee the transfer of that IV stat.
For example: if you were to give the Pokemon in the Daycare a Power Weight, then the offspring will have the same HP IV stat of it's parent who held that item.
The IV Judge in Kiloude Pokemon Centre will tell you what IVs it has.
I have phantump in the friend safari, so if you want my friend code tell me in the comments section down below.
Otherwise, I would have to resort to finding and catching a horde Pokemon with the hidden ability, using the power items to boost IVs whilst trying to get the right nature (when you do give it an everstone) and hope for the best!
Hope this helped!