The patch notes for the 5.3 PTR was recently updated. [source]
Here's a summary of all the updates and changes.
- You can duel (pet battles) with your raid and party members in dungeons and raids.
- Wild battles and duels can be viewed by everyone, not just the participants.
- There are updates to hit and miss/dodge chances. The base chance to miss or be dodged has been removed in battles between pets of the same level. Additionally, the chance to miss when fighting a higher-level opponent was reduced.
- The in-game statistics window will now track your max-level matchmaking PVP wins.
- The Pet Journal will save your choice of abilities for each pet when you swap them out of your active pet team.
- Family-specific battle-stones are now BoA.
- The Beasts of Fable daily quest has been broken up into three parts. You can complete any or all of them, and receive up to 3 daily bags per day. Additionally, these dailies will also reward a new consumable that boosts your pet's experience gain for a period of time.
You can check out the full official patch notes here.
The PTR is coming along, it's a wonder what other interesting features they will come up with next!