I do pulled chicken with Breasts all the time, it's great for me since I tend to feed no more than 3 people regularly.
As far as season goes, I just used whatever I have around. McCormicks Applewood, or Harry Sou's Champion Jailbird.
My preference since I recently bought it, is go buy Jeff's Rub Recipe.
I coat my chicken breasts with some maple syrup or olive oil, and than coat them heavily with the rub a couple hours before going onto my grill. Get them up to the 165 needed. Put them on my cutting board, chop up with my Bear Paws, back into an aluminum pan, coat them with bbq sauce, than back onto the grill over the fire for about 5 minutes, toss the chicken around a little, 5 more minutes.
Also like to toast the buns on the grill to make them a little tougher, helps to prevent bbq sauce from soaking into the bun too quickly. Makes for a much better sammich imo.