WoW Pet Battles: The System
The new WoW pet battle system will be accessible to all players from a low level. There will be both PvE battles against Wild Pets (see below) and PvP battles against other players and their battle-ready companions:

  • The battle system will be simple turn-based combat and is intended to allow battle with almost every existing pet.
  • All new pets introduced in MoP will be able to battle.
  • Entering into a Pet Battle, you will see your opponent and the three pets you will be fighting against, but you will NOT see your opponent's name or be able to communicate with them.
  • While in a Pet Battle, you will be able to switch between the three pets you've chosen to fight, and they will dutifully run up to your opponent's pet to attack it.
  • Challenging another player in the open world will switch you into a unique zoomed in view. Once combat is over it will return you to a normal gameplay camera view.
  • No one will ever have a significant advantage based simply on the rarity of a pet.
  • You can battle with your pets in solo matches or teams of up to three pets that you can create and perfect.
  • There will be a queuing system (like PvP battlegrounds) so that you will be able to find a match relatively quickly. You will also be able to duel with nearby players.
  • In addition to being able to queue into a queuing system and duel other players in the open world, there will be NPCs and critters that you can enter combat with to help level your mini-pets.
  • Unlike PVP, your Pet Battles stats will only show you how many games you've won. Information on losses will not be available.
Pet Leveling and Abilities
Every pet can use up to three abilities in a given battle with a total of six abilities to swap around in between battles. Here are some additional hightlights:
  • The pets that you own will have a corresponding "pet card" that will show all the information about said pet. Such information includes mini-pet health, level, attack, defense and movement speed values.
  • Winning pet battles will earn experience for your pets and help them level up.
  • Each mini-pet will have 6 abilities that players can choose pre-battle. Much like player leveling, as your companion levels up it will unlock more abilities. Also like a player talent tree, you can only choose one ability per row of talents for your pet.
  • The intended pet level cap is 25.
  • Every time you level your pet, you will also increase its stats.
  • There will be Pet Masters throughout the world who will let you earn Master abilities when you defeat them. These abilities can be taught to any pet.
  • You'll be able to manage your teams and battle abilities using a new UI widget known as the Pet Journal.
Pet Collecting Improvements and Customization
Your Pet Journal will display info on all your pets, including stats, skills, drop locations and lore. Through your journal, you'll be able to further customize your pets:
  • The pet UI will be updated to show you a list of all the pets you currently have and the pets that you don't have. In the case of the companions that you're missing, it will show you where to find those pets.
  • Account wide pets have been confirmed. All your characters will have access to all of your pets. This will cut down on switching between characters to level up a certain pet.
  • Developers are considering allowing players to grow their own mini-pets on personal farms within the Valley of the Four Winds.
  • Most pets will become tradable (even after being leveled).
  • You will be able to customize the name of each of your pets. This name will appear in battle.
  • You can obtain vanity items for your pets. Some of these items may offer combat bonuses.
Wild Pets
Wild Pets are discovered throughout the game world, some being more rare than others. To collect one, you'll need to engage it in battle (with one of your current pets) and defeat it.
  • There will be about 100 wild pets all over Azeroth you can collect.
  • There is likely to be at least one unique wild pet per zone.
  • Wild Pets will have random stats.
  • Many wild pets will be good at filling a specific role on your battle team, such as tanking or crowd control.
  • Some wild pets will only be found under certain conditions. For example, some of them will only spawn in the spring, or while it's raining, or during the nighttime.
http://www.warcraftpets.com/wow-pet-battles/


List of all Companion Pets

WoW-Wiki on Pet Battles

Trainers: *** Cost to Train 95 gold ***

Location Battle Pet Trainers
Razor Hill, Durotar Narzak
Bloodhoof Village, Mulgore Naleen
Brill, Tirisfal Glades Ansel Fincap
Falconwing Square, Eversong Woods Jarson Everlong
Goblin Slums, Orgrimmar Matty
Orgrimmar Varzok
The Golden Terrace, Vale of Eternal Blossoms Gentle Sanω

Quests
Once a player visits a Battle Pet Trainer and learns Pet Battle Training, they learn how to battle, level, heal and capture pets with a short questline.
  1. [85] Learning the Ropes
  2. [85] On The Mend
  3. [85] Level Up!
  4. [85] Got One!

Notes
Although classified as one of the above types, companions such as humans, orcs, kites, and balloons will not fight. Those that will not fight are:
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***** Extra companion pets can be caged and traded or sold on the Auction House.