So what kind of guy travels to the middle of a dark creepy cemetery and thinks:
This looks like a great spot for a summer home. While I'm at it, why don't I adopt some of the native wildlife?
The kind of creepy Worgen that likes to taunt you about his spiders' feeding habits every time he kills one of your poor little buddies. That's what kind of guy!
So you've bested the level 5 bunny girl. Now for something a bit more challenging. And by "challenging", I mean: "really annoying and possibly fatal to your pets." To begin with, your pets should all be level 7 if they want to match up against his eight legged gang. It would also be nice to have one that does well against beasts. A Mechanical would be great, but a Flying pet works too. If you have a Critter pet you want to use, be very careful with it. Shall we begin?
Webwinder is a Beast. He likes to eat your pets. But first he likes to wrap them in his Sticky Webs and use his Poison Spit to take down their health. He's probably the most annoying of the three because, even if you manage to kill him first, he will still regularly kill the pet you attack him with as his Sticky Web prevents you from swapping out for two turns. So if his poison doesn't finish you off, his next pet will still get a good chance at a free kill. If you have a chance to swap that first pet before it dies, you should take it.
Blackfang is also annoying. He doesn't hit as hard as Webwinder but he can heal himself with Leech Life. This makes him die a little bit more slowly. Leech Life also heals for twice as much if you are webbed, it hits harder against Humanoids and weaker against Aquatic pets. Really, the only thing you can do for most pets is to damage him harder than he can heal himself. However, if you have a burrow or dodge ability, try and time it to avoid either his Sticky Web or Leech Life.
Darkwidow is the least annoying, which isn't saying much. Instead of Sticky Webs, she uses Brittle Webbing. This ability doesn't prevent you from swapping, but instead damages you every time you damage her. She also has a poison and this weird ability called Spiderling Swarm which hits extra hard if you are webbed. The key to her is to use big attacks, instead of lots of little attacks, as this will reduce the damage you take from Brittle Webbing. And remember you can swap if you need to.
In Summary: Try and start with a pet that does well against Beasts (like a Mechanical or Flying pet). If you have the chance to swap pets on the first two, and your health is low, take it.
RNG can be a factor, so don't worry if it takes you more than one try. If it gets too frustrating, you can try and level one or more of your pets to 8 and then your extra speed and hit points can make the difference. Finally, don't expect all of your pets to survive! Your surviving pet will get a ton of XP, even if your dead ones don't.