I fought a player with 2 level 1 pets and a single level 14 Panda Cub. I myself had a Tanky Warbot with 600 HP at level 10. I literally get one-shot, non-crit, by the Panda Cub. Mind you, Panda Cubs are BEASTS and Warbots are MECHANICALS, which SHOULD mean I have the upper hand by doing 50% extra damage, certainly not equating to losing by OHKO.
My friends are reporting similar situations with Collector's Edition and Battle Store pets.
Seriously, Blizzard? I'm starting to understand why you guys introduced this system. When people complain that paid and collector's edition pets are OP you and most other players can just say "it's a casual mini-game, no one cares". Seems like this is where you're resorting to making your money from micro transactions.
EDIT: Typo, I have SIX-hundred HP, not four.