You know how Blingtron fights other Blingtrons right,
and how the winner gets bigger and buffed every fight.
Now imagine that non-combat pets, can turn into combat-pets with a checkbox or akin to (warmode) press on or off, more of a opt in option.
In doing so, non-combat pets actively fight each other of the opposite faction
I’d imagine it so you cannot attack, heal or buff them (except for certain toys) just to keep them separate, but as a cool aesthetic distraction.
Basic Template
pets auto attack, and randomly cast 1 of their 4 abilities.
every kill their size gets bigger, and casts an additional 1 of their 4 abilities uptil cap of 4
every kill, it grows in size. (no cap on size)
kill modifier buff lasts 5mins
dismissing pet removes buff
Could come with its own achievements and or questline or ;
New Battleground (I saw someone else suggest Pet-Battle BG’s)
https://us.forums.blizzard.com/en/wow/t/suggestion-pet-battle-bgs/367691