Account-Wide Collections and Pet Journal
In the pre-MoP patch, pets will be merged into a single collection. Companions will be account-wide and accessible from any of your characters, even those on other servers on that particular account. Also, if a character that initially learned a companion is removed, your collection will still retain the pet.
Unfortunately, players will not be able to summon and use any pets that are faction-specific. [source]
These pets include, but may not be limited to:
- Argent Squire or Gruntling
- Guild Herald
- Guild Page
- Horde or Alliance Balloon
We have yet to confirm if the faction-specific Moonkin Hatchling will also join this list.
In addition to account-wide collections, the Pet Journal will be making its debut. This unique and updated UI will hold all of your companions as well as provide extra information, such as health stats and the source for each pet.
Because of the introduction of the Pet Journal, the companion tab in the spellbook will be removed, and pets will only be accessible through the new journal interface.
It was mentioned in the Pet Battles FAQ that multiple versions of the same pet from multiple toons on an account will be merged into one in the Pet Journal. Extras will be placed in your inventory and/or mailed, however, it's unclear if this is intended to occur as soon as collections become account-wide or after Pet Battles is released.
What Will Not Be Available Pre-MoP
Pet Battles will not be available for play in patch 5.0.4. This new minigame will unlock on the release date of the retail version of MoP, but will not require the expansion. [source]
Although we will have to wait for this awesome new feature, with over 200 new wild pets to collect alone (not including all the new companions that can be collected through traditional means), it will certainly be worth the wait!