Just did this with 3 Saurolisk Hatchlings (BfA vendor pets)
Just used Rend, Burrow and Feign Death, but I am sure someone skilled could find a use for Rampage on one of them.
Feign Death always goes first, like Deflection so you can avoid the Void Gates. Rend and burrow work well together as you can cast rend and then burrow and the speed buff falls off. Then you can be undergound for a flurry and a void gate.
Took quite a few tries, but the pets were easy to get. Had him to 1 hp once, and 200 ish quite a few times. Some of the fights went 35 rounds, so it's not easy to give a real strat.
Only strat that worked for me, cred to Istalri on Wowhead:
NOTE: As far as I can tell, there is no replacement for the Nightmare Whelp. This strat requires the stacking healing debuff making Round 11s heal always equal 0.
Nether Faerie Dragon H/P (Life Exchange)
Nightmare Whelpling H/P (Call Darkness, Nightmare)
Chrominius H/H (Bite, Howl, Surge of Power)
R1) Nether Faerie Dragon Pass*
R2) Nether Faerie Dragon Swap to
R3) Nether Faerie Dragon Life Exchange
R4) Nether Faerie Dragon Pass*
R5) Chrominus Bite
R6) Chrominus Howl
R7) Nether Faerie Dragon Swap to*
R8) Nightmare Whelpling Call Darkness
R9) Nightmare Whelpling Nightmare (If Whelp dies, battle will be a loss)
R10) Nightmare Whelpling Pass*
R11) Chrominus Howl
R12) Chrominus Surge of Power
The Infinite Hatchling has to die on Turn 3; if not just give up.
Yula has to be dropped to 117 health, so save Life Exchange if Snozz only hits her one time and Breath instead.
It really really helps if you can get a critical hit.
I didn't succeed before all these things happened. Perservere!
This is IMO the hardest fight for the Family Fighter and I purposefully left this fight for last. Once I finally succeeded, I decided to share the Strat I used to win. Warning: There is heavy RNG BUT it neither involved 3 weeks of farming Celestial Tournament for Yula nor needed a rare/specific breed of Twilight Clutch Sister (which I was waiting over 2 week for on the AH).
1st Pet: Nether Faerie Dragon: x/2/1 I highly recommend (H/P) breed with 1465 health because:
A) The large health pool will allow NFD to survive 3 attacks from Snozz, reducing RNG
B) A wild Nether Faerie Dragon's most common breed to catch is (H/P)
Possible substitute for NFD: Yu'la or Sprite Darter Hatchling. But honestly, why are you here looking at this strat if you have Yu'la?
DISCLAIMERS: 1) This is a HEAVY RNG fight requiring AT LEAST 1 of 3 possible critical strikes. 2) 2nd pet (Dark Whelpling) must have more health than the 3rd pet (Azure Whelpling). 3) I didn't test it myself nor would I ever do this fight again but... A friend informed me the Albino Chimaerling as the 2nd pet and Emmigosa as the 3rd pet is not a viable combination. 4) Call Darkness is vital to this strat. It's "buff" will reduce accuracy of all pets by 10%. If this causes one of your attack to miss then restart the battle. 5) IMPORTANT bring bandages and have patience. Unless you're really unlucky, this shouldn't take more than 25 tries.
Now on to the Strat:
Round 1: NFD is forced out to Dark Whelpling (or 2nd pet). Round 2: Swap Dark Whelpling back to NFD Round 3: Life Exchange. It's uncommon with (H/P) breed but if NFD dies BEFORE life exchange; restart the fight. Round 4: NFD is forced out to the Dark Whelpling (2nd pet). Round 5: Call Darkness (Hope for a critical -- it's rare but if you don't get one don't worry, just continue. You'll have two more chances to get a critical). (Additionally If you miss any of the next 4 attacks as a result of Call Darkness' 10% reduced accuracy then restart the battle). Round 6: Tail Sweep Round 7: Dark Whelpling (or 2nd Pet) is forced out to Azure Whelpling (or 3rd pet). Round 8: Claw (Hope for a critical). Round 9: Surge of Power (Hope for a critical). If Azure Whelpling is hit more than 5 times by Snozz's flank prior to casting Surge of Power then Azure Whelpling will die and you must restart the battle.
GG! If you made it this far, you've won. And if you saved this for your last pet battle for the family fighter achievement, then you can hearth from this frustrating hellhole and never look back.
Please comment if it worked for you! Or comment if you see room for improvement!
37 times using this strat with the breeds suggested and no luck. Tried the original strat 25 times and no luck. One of the most rng fights I have ever encountered and the last I need to the meta pet battle achv in Argus. Not sure what to do at this point, very frustrated.
Worked third time for me so maybe lucky. 1st time the Azure Whelpling did not get swapped in as expected, second time the NFD died before life exchange (it was a P/P though), 3rd time I hit the crits on Azure, yehhh.