Wailing Critters

once you beat the everliving spore (i almost soloed him and his companions with one jellyfish) and the quest is complete, it tells you to return to muyani at the wailing caverns. if you jump down to where she is, she will tell you that you have to battle your way to the boss and gives you the option to exit the dungeon if you talk to her. when you select this option, it says you will lose all progress in the scenario and are you sure. as long as the quest is complete, you are fine. take her offer to exit the dungeon.

You can also drop group.

The Wailing Critters dungeon opens with patch 7.2
You will need 1 level 25 pet to start the initial quest, and 3 to do the following challenge mode (no healing, no reviving).
In order to beat the challenge, you will however need a few more pets.

Here is the list I was able to do it with on the PTR:

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• Emerald Proto-Whelp (1 is enough but having 2 is safer)
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• Cogblade Raptor
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• Cinder Pup
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• Ikky
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• Cerulean Moth
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• Mechanical Pandaren Dragonling
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• Iron Starlette
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• Darkmoon Tonk
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• Darkmoon Zeppelin
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• Pandaren Water Spirit
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• Teroclaw Hatchling
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• 2 Beast pets on level 25
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• 5 more pets of any sort on level 25
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It's 11 fights that you need to do and the Emerald Proto-Whelp (2 2 2) is the essential pet here. Thanks to its self-heal, it can clear the first stage and will then be in almost every other fight to clean the enemy backline pets.The other pets are interchangeable with what you have.

Listing all strategies here would probably be a bit messy. You can find them outlined in more detail here: https://wow-petguide.com/index.php?m=WailingCrittersC
The fights are not very hard though and if you have a large collection of leveled pets, you won't have much trouble with this dungeon :-)