I should preface this guide with the following: Pet Battles is not a quick and short activity. It's a long adventure that requires time, knowledge, and effort. However, it gets progressively easier as you collect and level more pets.
It's all about power gain. Your pets and their quality and level are your power in Pet Battles. The more pets you have, at higher quality and level, the easier things will become.
That being said, here are just a few ways you can level your battle pets (relatively) quickly. There are many strategies, ideas, and so on. Pick what feels acceptable for you.
This guide is not a full Pet Battle guide. It requires some basic knowledge of the system/mechanics involved. This guide simply provides suggestions on how to acquire your first level 25 pet, what to do with it, and how to get more max level battle pets.
For a guide to Pet Battles in general, check out WarcraftPets or Wowhead.
I did not come up with these ideas. A big thank you to users on WarcraftPets Forum, Wowhead, Bnet Pet Battle forums, and individual persons for suggesting these.
►►Getting your first level 25 pet (and then some)
Important!: The purpose of your first level 25 battle pet is to help you get more max level pets. Keep this in mind when choosing your first pet to level up.
Strategy 1 - 'Intended progression path'
The original progression path starts in Orgrimmar or Stormwind. Speak with the NPC that teaches you the Pet Battle skill and accept the quest. This will start the long quest chain that will take you through each zone to battle trainers, each with increasing level and difficulty. (List of zones by pet level)
To supplement pet levels between trainer battles, you'll want to challenge wild pets. Capture any rare quality (blue) wild pets that you come across to help bolster your collection. As you climb into higher level pet zones, the pets you capture will help add to the overall level of your collection. Remember: More pets, higher quality, higher level = more power = easier to complete content.
Completing the intended progression path (Pet Battle quest chain) will be extremely beneficial in the end. You will unlock trainer dailies of varying level that, at higher levels, can be used to efficiently power level your battle pets.
Strategy 2 - 'Progression path too long; I have a lot of gold and am willing to spend it'
Want to skip the quest chain? Ok. If you have zero level 25 pets, head to Draenor and get yourself a level 3 garrison and unlock the Menagerie. Complete the quest Unearthed Magic for a free Ultimate Battle-Training Stone.
Use this battlestone on which ever pet you feel you use the most that you currently own. Alternatively, you can purchase a level 1 pet from the Auction House and use the stone on that (most people recommend the Anubisath Idol).
IMPORTANT: You can only add purchased pets of the same level as your highest level pet that you currently have in your Pet Journal. So now that you've boosted one pet to 25, you can head to the AH and purchase and add any other level 25 pets that you want.
It may not be cheap, depending on your server, but it's a fast way to get a decent army of pets ready for Pet Battle content.
Note that there are some pets listed in guides that you cannot trade or buy. You will need to use your newly purchased collection of level 25 pets to go out and capture them in the wild.
Strategy 3 - 'I DON'T have a lot of gold and/or am unwilling to spend it'
This method is better paired with Strategy 1; you'll be grinding on wild pets so why not add in some trainer battles too?
If you have zero level 25 pets, head to Draenor and get yourself a level 3 garrison and unlock the Menagerie. Complete the quest Unearthed Magic for a free Ultimate Battle-Training Stone.
Use this battlestone on which ever pet you feel you use the most that you currently own. Because you will be doing a lot of grinding on wild pets, you should pick a pet that can "carry" lower level ones. This means the pet you choose to boost to 25 should be able to finish fights on its own or with very little help.
You can try and obtain an Anubisath Idol and boost it to 25 with the battlestone, but it will be very RNG dependent as this pet is a drop from a legacy raid boss.
►►How to use your first level 25 pet to level other pets
Method 1 - Capture a higher level wild pet
One way to add to your team of one is to take your level 25 pet and go to Deadwind Pass. Battle and capture an Arcane Eye (wild, is a solo pet so you don't have to fight other pets). Because the pet level of the zone is higher, you'll automatically get a higher level pet.
If you go this route, be sure not to use your level 25 battlestone on a pet that's weak against the Arcane Eyes. Weak against Magic attacks: Flying; weak attacks against Magic: Aquatic. Do not boost these two pet families if you plan on using this method.
Level up your Arcane Eye on other Arcane Eyes (with the help of your first 25 pet), and once it reaches roughly level 20+ (higher level the better) go to Dragonblight in Northrend. Large packs of wild Flying pets spawn in Dragonblight (near the exposed bones) and your Arcane Eye is strong against Flying.
You can use your Arcane Eye on any wild Flying pet, not just the ones in Dragonblight. They are simply the most convenient as they spawn in large groups and have a decent respawn time.
Use the Dragonbone Hatchlings to finish leveling up your Arcane Eye. You can use your first level 25 pet to help, and even add in another lower level pet to leech some levels once your Arcane Eye is 25.
Caution: Dragonbone Hatchlings can spawn with the Cyclone attack, which can potentially ruin this method.
Method 2 - Battle Aquatic wild pets
Boost a turkey (any works), level up a second Flying pet (moths are good), and head to Vale of Eternal Blossoms in Pandaria. Since your turkey is Flying, it's strong against Aquatics, so you want to find Aqautic pets to battle.
Use the turkey's ability Food Coma to crowd control the first enemy pet, swap in your lower level pet, swap it back out for your turkey, and finish the fight with your two Flying pets.
Flying will work well against most Aquatics found anywhere, but like the Dragonbone Hatchlings in Dragonblight, the wild pets in the Vale of Eternal Blossoms are convenient and relatively plentiful. They also usually spawn with 2 additional Aquatic pets, making it easy to level up Flying pets (like the Falcosaur Hatchlings!).
Method 3 - Battle Beast wild pets
Use your Ultimate Battle-Training Stone on a Mechanical Pet with Decoy (Darkmoon Zeppelin, Alarm-o-Bot, Lifelike Mechanical Frostboar, Race MiniZep). This is essentially the same as Method 2, but instead of fighting Aquatic pets, you want to find wild pets that are from the Beast family.
Frostfire Ridge in Draenor is excellent for grinding pet levels against wild Beast pets.
Set up Decoy, swap in your lower level pet and then out again, and finish the fight with your two other high level pets.
►►Efficient use of multiple level 25 pets to help level other pets
Option 1 - Grind wild battles
Just do wild battles using two level 25 pets and one low level.
Option 2 - Trainer dailies.
This calls back to Strategy 1 for getting your first level 25 pet. Complete the Pet Battle quest chain and unlock the trainer dailies in Pandaria (requires full clear of all trainers of Kalimdor, Eastern Kingdoms, Outland, Cataclysm zones, Northrend, and Pandaria).
If you've defeated 40 trainers (which is likely if you've completed all of the achievements above), you will receive a Safari Hat. Using it will increase the amount of pet experience your battle pets receive by a bit.
Using the trainer dailies to help power level pets is extremely efficient, as the battles give amazing amounts of pet experience. (Read more about different amounts of pet experience gained from different encounters of varying difficulty.)
On top of granting large chunks of pet experience, the Pandaria dailies also reward pet bags which have a chance to drop battlestones. You can use these to upgrade your pets!
There are many guides on how to use the Pandaria Pet Battle dailies to power level pets. Here is one from WarcraftPets that details which two level 25 pets you need for each battle. Here is one for Draenor trainer dailies (unlike Pandaria dailies, these don't have any prerequisites). They're outdated, but most of the information is still great advice.
I recommend using the Ashlei battle in Draenor first to carry a level 1 pet, and then heading to Pandaria to complete the trainer dailies.
►►Things to note
■ To "carry" a lower level, you want to make sure it doesn't take any damage. It only needs to be your active pet for one round, so swap it in when you feel the enemy team will use a move that does little to no damage, and then swap it out for one of your higher level pets to finish the fight.
You don't want to battle wild pets that have a team-wide AOE. Pet families that can spawn with AOE attacks or persisting damage (but not always): Flying, Magic, Elemental and certain Critters. Be wary of using these for leveling sub-level 5 pets.
■ Be sure to capture any rare quality (blue) wild pets that you don't already have.
■ Once you have a handful of pets at max level, you can head to any zone and battle the wild pets there. The higher the level of the zone, the higher the level of the wild pets.
►►Stand out "carry pets" for grinding pet levels
This list is subjective, however there are some pets that are often recommended due to their power and survivability.
I've ranked these pets based on my own preference (1 being top tier). Other pet battlers may rate them differently.
1 Anubisath Idol
1 Feline Familiar
1 Mechanical Pandaren Dragonling
1 Emerald Proto-Whelp (obtainable only from the wild, prefer Power stat)
2 Darkmoon Zeppelin
2 Any cat (must have the Devour ability, prefer Power stat)
3 Any moth (the more Power stat it has the better, usually)
3 Any snail (the more Health and Power stat it has the better, usually)
Have any additional tips and tricks for leveling pets? See any errors or incorrect information? Leave a comment below!