If you use the Sekrit Pets Addon on the PTR, you can access a bunch of hidden pets, ranging from test pets like "Jacob the Test Seagull" to NPC pets like the ones from the Fabled dalies. Has something to do with the random pets you get on your PTR characters.
Doing this I was able to have fun with this guy:
Lil' Oondasta! I believe he's going to be able to be fought on the Timeless Island, maybe as part of the Celestial Tournament. Not meant for us mere mortals, but it's fun playing with him!
Here's the actual numbers, which are pretty hilarious:
Frill Blast (5rd cd)-- 1522 Spitfire Beam (3rd cd)-- 571 each pet Crush -- 1065
But because he's slow it should be easy to beat him: mechs will get at least 2 attacks each, one of which will be Ion Cannon, and they're resistant to the magic damage. Lightning Storm + Ion Cannon + Ion Cannon + Ion Cannon is already ~2200 damage (assuming he's got the 50% damage reduction like other legendary pets). Or, start with any pet with Stampede, get the double damage debuff up, wait for that pet to die or get Frill Blasted, then freeswap in Yeti for Lightning Storm + Ion Cannon = 2700 damage. If they don't fix how Howl/Stampede interact with the legendary pet damage reduction, that should continue to be an easy route to beating these.