Pet Battle Challenge: Deadmines

My TL;DR shopping list of pets for this dungeon, followed by a quick walkthrough:

Phoenix Hatchling
Spring Rabbit (or any rabbit with dodge/flurry/burrow)
Amber Moth x2 (or any generic moths)
Alpine Foxling x2 (or any beasts with Howl/Bite)
Emperor Crab
Iron Starlette
Unborn Val'kyr
Zandalari Kneebiter (or any Zandalari pet with Black Claw/Hunting Party)
Darkmoon Tonk
Hyjal Wisp
Nexus Whelpling x2
Emerald Proto Whelp

INTRO

The Deadmines pet battle dungeon is similar to the Wailing Caverns event, except this one has nine fights instead of 11, and the backline pets here are parrots, rats and crabs. This means you'll want to fill out a lot of teams with flying, beast and magic pets. (I just used a variety of moths and foxes.)

Interestingly, the lead pets for these nine battles are eight different pet types, which gives this dungeon a little more variety, and should take less time (nice, so weekly clears don't feel tedious).

STAGE 1

FOE REAPER 50 (mechanical) - no backline pets
- This is a boss, who resists 50% of all damage and can't be one-shot for more than 35%, but I was able to solo this using a Phoenix Hatchling. Foe Reaper does backline damage, so you might want to use two throwaway pets as backups. A Pandaren Water Spirit is also a good choice here.

STAGE 2

UNFORTUNATE DEFIAS (undead) + 2 backline pets
- You can use just about any rabbit with dodge, flurry and burrow for this unfortunate skull -- I used a Spring Rabbit and mopped up with an Amber Moth.

ANGRY GEODE (elemental) + 2 backline pets
- An Emperor Crab with Whirlpool will have little trouble with the lead pet.

STAGE 3

MINING MONKEY (beast) + 2 backline pets
- An Iron Starlette can one-shot this simian with the familiar Wind-up/Supercharge/Wind-up combo, and should be able to take out the second pet as well. I used a moth to clean up the leftovers.

STAGE 4

"CAPTAIN" KLUTZ (humanoid) - no backline pets
- This one can be a little tricky -- he stuns on the opening move, and also heals. However, an Unborn Val'kyr with Curse of Doom and Unholy Ascension and any Zandalari pet with Black Claw and Hunting Party can dispose of him quickly.

STAGE 5

KLUTZ'S BATTLE RAT (critter) + 2 backline pets
- This is a pretty simple fight -- I used the same Zandalari Kneebiter from the previous fight to kill the opening rat and most moth/beast combos should take care of the rest.

KLUTZ'S BATTLE MONKEY (beast) + 2 backline pets
- A Darkmoon Tonk took the monkey out without any trouble, and Minefield will give you a headstart on the backline pets.

KLUTZ'S BATTLE BIRD (flying) + 2 backline pets
- This bird is elite and blocks half your damage, but it's possible to solo this entire fight with a Hyjal Wisp, using its dodge and heal abilities.

FINAL STAGE

COOKIE'S LEFTOVERS (magic) -- no backline pets
- This final boss does an opening stun and can hit pretty hard, but I was able to beat it pretty easily with 2x Nexus Whelpling, using Arcane Storm and Mana Surge. Tail Sweep also hits pretty hard once Mana Surge is on cooldown, and I also kept an Emerald Proto-Whelp as my third pet just as backup.

There are obviously more strategies and pets that can be used for these fights -- hope this is useful to anyone who might be stuck!

Deadmines, Battle pet dungeon how to:

Stage 1:
1st Encounter Boss [npc=119409] with 50% damage reduction and a maximum of 35% of its total HP taken per hit. With no backline pets.
Type: Mechanical. Soloable by an Elemental pet like [npc=62621] using [pet-ability=113], [pet-ability=178], [pet-ability=179].
Notes: This boss is using [pet-ability=923], so use one more elemental pet as backup and one pet that you are not gonna use further in this dungeon.

Stage 2:
2nd Encounter [npc=119346] with 50% damage reduction and 2 backline pets of common quality from Aquatic, Flying or Critter family.
Type: Undead. Soloable by a [npc=61080] or any other pet from its family using [pet-ability=360], [pet-ability=312], [pet-ability=159].
Notes: Nothing special about this pet to mention.

3rd Encounter [npc=119342] with 50% damage reduction and 2 backline pets of common quality from Aquatic, Flying or Critter family.
Type: Elemental. Soloable by an Aquatic pet like [npc=65203] using [pet-ability=509], [pet-ability=123], [pet-ability=310].
Notes: This pet has [pet-ability=436] & [pet-ability=569] abilities and this fight may take a bit more time to win.

Stage 3:
4th Encounter [npc=119341] with 50% damage reduction and 2 backline pets of common quality from Aquatic, Flying or Critter family.
Type: Beast. Soloable by [npc=77221], with the usual combo.
Notes: Nothing special about this pet to mention.

Stage 4:
5th Encounter Boss "Captain" Klutz with 50% damage reduction and a maximum of 35% of its total HP taken per hit. With no backline pets.
Type: Humanoid. For this fight you will need 2 pets. You can use the combo of [npc=71163] with [pet-ability=652] & [npc=69796] with [pet-ability=919]
& [pet-ability=921] to win, or you can try any other combo like [pet-ability=321] & [npc=34770]'s [pet-ability=1093], which is not that strong.
Notes: This boss is using [pet-ability=350] to stun your pet and [pet-ability=1012] to heal, making this fight the hardest one in the scenario.

Stage 5:
6th Encounter [npc=119343] with 50% damage reduction and 2 backline pets of common quality from Aquatic, Flying or Critter family.
Type: Critter. Soloable by [npc=71942] with [pet-ability=595] & [pet-ability=974], or [pet-ability=536] & [pet-ability=110].
Notes: Beware of its ability [pet-ability=293] witch is a strong attack vs Beasts. it may not end up well for your pet. Killing this pet as soon as possible will ensure the win.

7th Encounter [npc=119345] with 50% damage reduction and 2 backline pets of common quality from Aquatic, Flying or Critter family.
Type: Beast. Soloable by a lot of Mechanical pets like [npc=80329], [npc=48609], [npc=61160], [npc=115140] and many others.
Notes: Nothing special about this pet to mention.

8th Encounter [npc=119344] with 50% damage reduction and 2 backline pets of common quality from Aquatic, Flying or Critter family.
Type: Flying. Soloable by [npc=68845] with [pet-ability=589] & [pet-ability=489] combo.
Notes: Nothing special about this pet to mention.

Final Stage:
9th Encounter Boss Cookie's Leftovers with 50% damage reduction and a maximum of 35% of its total HP taken per hit. With no backline pets.
Type: Magic: Soloable by a [npc=64899] with [pet-ability=115], [pet-ability=779] and [pet-ability=334]. [pet-ability=779] does the most damage on him, so use it on cooldown.
Notes: This boss is using [pet-ability=580] to sleep your pet and [pet-ability=1016] to heal itself. Avoid sleep by starting the fight with [pet-ability=334].

Good luck and have fun. May the battles begin!

After killing the last boss, just "Leave Instance Group," and you will end up next to [npc=119390] to turn in the quest. No need to retrace your steps back through the entire dungeon or jump off the ship toward the cave or anything else.