No Secondary Ability. The concept was to give this CAP an ability that hasn't really seen much use in standard, due to only really appearing on mediocre Pokemon. Going with two abilities makes it more difficult to accomplish this goal, as instead of simply making sure CAP8 can make good use of its ability, we'd have to make it well-capable of using both, and not really have one ability stand out too much above the other. As EM pointed out, like it did with Stratagem, this may make things a bit messy during movepool, so I'd rather avoid that by having us just stick with one.
Plus, none of the abilities left really stick out to me anyway. The most commonly used moves against this Pokemon will be things like EQ, Ice Shard, and Ice Beam, so Rough Skin won't be that useful. Having to actually take a status problem makes Marvel Skin not really that useful as even RestTalk sets, the best option with it, really have their issues (not selecting the right move/not attacking at all). Things like Static are too unreliable and will most likely end out beign outclassed by Shield Dust. Hustle is basically only good for hitting things like Blissey and Snorlax (as most other things are stronger on the Defensive side anyway) and even then, it's unreliable due to the accuracy. Things like Rock Head and Mold Breaker sound interesting, but it really wouldnt be able to make the most of them.
I do personally like Thick Fat, though. However, I don't feel it should be on there, as I don't belive it's really neglected. Thus, NSA is really the way to go for me.