Nice!
Mine is Hadassa, the pet I chose from the pound in the tutorial. He is lvl 18 without the use of any items. Unfortunately he's tied up most of today making items since he's also one of my most intelligent pets. He has a weak beak but his steel muscles more than make up for that. He mostly just curb-stomps everything. Except the bosses, which just destroy all my pets in like one attack.
My starter Daria is worse off but still level 15. Not so good genes but I'll be chucking mutagen at her to see if that helps. (Or hurts!)
But I've been exploring with all my pets so on average they are level 10.