As it is now, it's rather boring with PvP (I know I ain't doing it at least).
You have pre defined team, and you challenge a random dude, that also got a pre defined team.
How fun is it if you use, for instance...3 humanoid against a group of pets with humanoid+damage abilities?
With all abilities all pets got (with bonus damage against familys etc.), then I at least hope that something like what I'll explain is in Blizzcrew mind.
Create 2 tiers of pet battle (for the Find Battle) option. One for level 1-23 and one for level 24-25. Make the 1-23 work just as it is now and the second one explained below.
To queue for second tier you need to have at least 3 level 24+ pets. You will then open an option to choose 10 diffrent pets, randomly from your Pet Journal, all level 24+. ALL these 10 will make your base team for Pet Battle PvP. You can choose free what you want here.
When you queue for a battle and both have pressed "Yes" to enter the game.
1. When you enter, both will get a timer for 10 seconds, to choose pet #1, and when they have done their choice it will get visible for both teams
2. Second timer start, and both get another 10 seconds to choose pet #2, meanwhile you can see what they choosed as #1 (but not which skills).
3. Last, a third 10 second timer and same conditions as earlier one.
This way it will make PvP more a brainer than just pure luck for your PvP battles. It will be more like chess if you know what I mean "Ahaa, he makes that move! Ok, then I counter with this!".
This will "force" players to get more tactical and save their "killer" for the last spot.
Either this one just explained system or this other one I have in mind.
Let us make 3 pre-defined teams to choose from for every PvP fight, and let us choose it when we're head to head, able to see at least all 3 teams and what familys every pet are (in that case, it won't spoil what skills they got, just says "Aquatic").
Also a timer for this, let's say 20 seconds to inspect their 3 teams and to choose your + skills.
I can just honestly say that if it stays as it is now, then I won't be doing it. Not even if they add really nice transmog-gear. But that's just me...