Wowhead has info on pets, pet achievements, suggested teams and strategies for each trainer. It is helpful for getting ideas for alternative teams here.
Warcraftpets is an excellent resource for battle pet research and info. There are many guides to pet battles, one of them is 5.4 Guide to Master Tamer (levelling) + Beasts of Fable by Rendigar that I used to make my own teams. It is very detailed and thorough and I highly recommend you read it for teams and strats, then adapt them to your collection. I am using his teams for Beasts of Fable and they are highly successful.
The next step is Celestial Tournament. I used Complete Celestial Tournament Walkthru and Pet list by Elfuego to build the list of pets that I needed to level for these teams. I'm still working on that because I don't have all the pets he recommends, so I'm having to find alternatives and they don't seem to work as well as his teams.
Elfuego has a whole site dedicated to pet battles www.wowpetbattle.com. He has videos, strategies, teams, and loads of info there. Sadly the site design makes it hard to read sometimes, but it's a goldmine if you find what you're looking for.
Intro Section I: Set Up Section II: Master Pet List Section III: Travel Route Section IV: Tamer Battles — Hyuna of the Shrines, Mo'ruk, and Farmer Nishi Section IV: Tamer Battles continued — Wastewalker Shu, Seeker Zusshi, and Aki the Chosen Section V: Further Reading