Cory Stockton (Mumper on the Mists of Pandaria
beta forums) has posted a clarification
to a forum thread about pet battles and PvP that explains exactly what you pet battle collectors on PvP servers can expect.
Mumper - Clarification Requested: PvP Vulnerability
The fact that players are vulnerable to PvP attacks while in a pet battle is intentional. However, a couple features that go along with this are not implemented yet.
First off, the exact pet you were fighting when you were broke out of pet battle will be respawned. Same quality, stats and skin color. Second, you will get a 3s damage shield that absorbs 50% of incoming damage to help negate the fact that you need time to recover after exiting the pet battle interface. Both of these will be in for the next build.
We feel its very important to keep the PvP aspect of the game intact and if you choose to play on a PvP server, you will certainly be fighting for those rare spawns. (This rule effects PVE servers as well but only in contested areas.)
So yes, if you're on a PvP server (like I currently am) and you intend to take part in pet battles and collecting wild pets (unlike me), then you'll have to contend with PvP in the world. The fact that you'll at least get to try again after you kill that rogue has to be of some comfort, but I personally didn't even expect that much. The damage shield to give you a fighting chance goes way beyond what I was expecting, quite frankly. On PvP realms, let the battlers beware!
It's open warfare between Alliance and Horde in
Mists of Pandaria,
World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!