Each battle that you win will yield experience for each pet that participated. However, deceased companions will not receive any experience (so make an effort to keep them alive by swaping in a different pet). Experience gains are based on your pet's level compared to the wild pet. Defeating a higher level opponent will grant more experience than a much lower level one, but be ready for a tough fight!
So tonight I took the plunge and thought hey let me buy a Zygor Guides subscription to see how it is. A guide backed by a subscriber base paying for a premium experience this has to be great right? I was wrong. I tested it by loading it up on the Honorboud Rep Guide. Cool it tells me to do World Quests and Island Expeditions. So far so good but hang on... What about the Wanted Quests? Those are by far the biggest boost to reputation. It did not mention them at all. So I thought that's fine it's probably because BFA is quite new. Loaded up a leveling guide on an alt. It was a complete mess. The guide was telling me to accept quests that A) would be horribly inefficient to level with and B) I already done. I also started noticing weird performance issues. Zygor was causing stuttering and FPS dips like crazy. So to close off I requested a refund and the person I spoke to did say I'll be getting one but we will see if that happens. Not getting my hopes up.
The vanilla WoW Horde leveling guide you see on this site was originally made back in 2006 by Joana (AKA Mancow, or FuriousPaul). The guides have been tweaked many times over the years to make things "faster". The leveling guides were made because of all the messages I got from people asking me how I was able to level up so quickly on new realms. I was first to level 60 on 7 different realms (3 with Mancow and 4 with Joana), even winning Blizzard's "First to Level 50" contest they held back in 2006.
The quality of captured wild pets is random. As of patch 5.1, upon entering a battle the Pet Battle UI shows the quality of a wild pet (idicated by a color-coded border around its icon). If you're farming a specific quality, if you forfeit the match your team will incur a small damage penalty (roughly 10%). There is no accurate way to determine a pet's quality prior to the start of a battle.
It was the experience of the game that brought pleasure and joy, and that's what a lot of us want again. Not the numbers. When I play Classic I want to go through the deadmines with people I like and overcome a challenge together and see myself become stronger as a result. I don't want to play Classic so I can say "booyah! That number is exactly the same as it was 13 years ago!"