Foreign Pokemon merely come from another part of the world. That is all. Hidden Abilities can come from two places in gen 6, aside from breeding and transferring from gen 5. These two ways are Hordes and the Friend Safari. Note that not every Pokemon in a Horde or Safari will have its HA. In fact, relatively few of them will. It's still your best bet for HAs, though.
Just so you know, foreign Pokemon do actually have a benefit of sorts, not counting those that all traded Pokemon have (for example, any Pokemon traded to you will gain XP faster). When you breed two Pokemon from different regions, say a German Charizard and a Japanese Salamence, the children will have higher odds of being shiny upon hatching. This is known as the Masuda Method. One of the two regions may be your own, so (assuming you live in America) you could have an American Pokemon and a Japanese Pokemon if you wanted. But that's all you get. Higher shiny odds, and they're still way low.
Warning: User is known to the state of California to get preachy.