Extra Pieces

What worked for me - Dust Bunny 2-2-2 (or another rabbit with Flurry, Dodge and Stampede and 322+ speed), Iron Starlette 1-x-1, Mechanical pandaren dragonling 2-2-2

Dust Bunny
Dodge
Stampede
Flurry
Dodge
Stampede
dead

Iron Starlette
Wind-up
Supercharge
Wind-up
Wind-up - enemy second pet should be after resurrection, Wind-up even thought he is low HP and will die this round, you will need it for the next pet,
btw, your Starlette should die and resurrect this round too
Wind-up - should damage the third enemy pet because it is slower
dead

Mechanical Pandaren Dragonling
Decoy
Flyby
Thunderbolt
Flyby

enemy dead

First try with this team, should work

Edit on January 5th 2021 - made a note to third wind-up as why to use it, did it multiple times with this setup, still works, last enemy pet should die the same round your Dragonling dies and resurrects, specification of my lvl 25 rare pets: Dust Bunny P/S (speed 322), Iron Starlette P/B (speed 257), Mechanical Pandaren Dragonling S/S (speed 309)

well i didnt have many of pets mentioned in the comments so i just used 3 lvl 1 pets that take reduce damage from them(a aquatic+beast+mech)
i hope this could help u cuz when u use 3 lvl1 pets their levels also reduced to 1

If you struggle with this pet-battle as much as I did, consider to bring 3 level 1 pets.
Best strategy here would be:

1. Leftovers: Aqua with a strong attack against Undead.
2. Leftovers: Beast with a strong attack against Undead.
3. Leftovers: Mechanical with a strong attack against Undead.

I had no matching Mechanical-pet but I went with Lightless Ambusher, Jenafur and Tinytron and it still worked.