Each pet that you own can learn up to six abilities, but only three of them can be used in the turn-based battle, so you need to carefully assign which you plan to use. Pet Battles will have a queue system just like dungeons and Battlegrounds, with one small difference: you will never see the name of the player you're facing off against. Blizzard wanted to minimize the "shame of defeat" that tends to be a barrier to entry in PvP -- nobody likes feeling bad when they lose. You will never know who you've lost to, and they can't trash talk you during or afterwards. While your statistics page will keep track of your number of wins, it will not track your losses.
Filed under: Mists of Pandaria