According to Mumper, there are more Pet Battle updates and changes coming to the beta in an upcoming patch. [source]
- Unique Tamer emotes
- Unique Tamer pets
- Tamer battles have been tuned up in difficulty
- One Grand Master Tamer per continent. Defeating him/her will unlock all the daily's on that continent.
- The flow has been consolidated to work though our two main trainers in Stormwind and Orgrimmar.
- They have implemented more than 40 Tamer fights across the entire game. This does not include the boss fights!
- Daily quests on Grand Master Tamers offer the Sack of Pet Supplies as a reward.
- A new achievement reward for defeating all the Tamers. A "Tamer" title.
- All of the quests to fight Tamers are now account-wide. This means that the one-shot quests can only be completed by one character on your account. The daily's can be completed by any character, once per day. Account wide quests are denoted in the quest log.
Warbot was available to players (USA only) in August of 2009, during the Mountain Dew Game Fuel special promotion. Along with this pet, eligible players received red and blue Warbot fuel that they could use on these unique pets so that they would engage in battle with other Warbots of opposing fuel color.
Once the promotion ended, both the companion and the fuel were no longer available.
However, in a recent announcement it was revealed that the Warbot fuel would be returning and players would again be able to obtain fuel and fill their pets with this charged up juice. [source]
There will be a way to get Warbot fuel in MoP. Still figuring out the specifics, but we are going to make it happen.
So not only will players and pets be able to engage in Pet Battles in MoP, Warbots will have the chance to fight each other outside of official encounters again. The big question: What color will you choose?