Is there one that stands out more than any other?
I really don’t do Pet Battles, but was wondering if there was an addon that made suggestions on best setup vs certain trainers?
I’d rather not have to alt+tab go goole each trainer and read a novel what I barely understand. I need a “Pet Battling” for dummies guide!
Rematch.
It remembers and recalls teams you make or import, and gives you a great search and filter of your pets.
It does not make guesses at best teams, but if you find a team at Xu-Fu’s
https://www.wow-petguide.com/
you can Export the team from Xu-Fu’s and Import the team into Rematch.
The other two must-have basic addons are
Battle Pet BreedID - which displays a pet’s breed for you
PetTracker - shows where to capture species on the map, and also has three small useful modules.
There are other addons for other purposes as well, but those are the first three you must get.
P.S. Pet Battles for Beginners, you say? 
Start here:
https://www.youtube.com/watch?v=e-PJIrVzvFg
^^^^^ What Grainne said…Rematch is a must for Pet battling…it lets you build teams that can be saved to use over and over …saves a lot of time once you got teams built up …and Xu-Fu web site is a must too…
real Chads dont use any addons and also type with one finger and use the arrow keys to move