I guess the best thing to do if you see a Pokemon that you know has Quick Guard is to take it out before you use your priority moves. I'm not entirely sure; Quick Guard is something I rarely have to contend with.
I'll help you as much as I can, but in regards to double battles, it would be better to hit up Griffinbane with questions, since she's the expert on doubles and VGC. The help I can provide on double battles is limited due to my lack of experience with them. Singles is my forte.
Cool. You might wanna get online on your X/Y right now, because Sableye is the 3rd poke in my Safari, meaning we have to be online at the same time at least once. I'm online on my Y right now.
I don't need anything in return. We just need to exchange Friend Codes, then you can catch one yourself from my Safari (I don't have one myself, you see).
My FC is: 0619-4178-0907. Add me and tell me yours so you can get into my Safari.