Earlier today, I was raiding safaris when I came across a Fairy and Fighting type safari that had Swirlix and Sawk repectively, which are Pokemon exclusive to X. I am playing Y. Is there a reason for this?
The Friend Safari has set Pokemon for each friend. As such, there is no exclusivity in it. If you friend has a safari with a Houndoom, for example, it will always have a Houndoom in it, regardless of which version you happen to be playing.