Leana Darkwind

2-pet + leveler:

alternative strat:

similar concept like the original strat below, but with less vulnerability to RNG.

[npc=66950] (2,2,2)
[npc=143053] (2,2,1) – any breed
Carry pet : 200+ hp (Mechanical and Magic pets with any hp)

vs. Elemental:
1. [npc=66950] > Geyser > Wave > Dive > Wave.
* last Wave will hit the Aquatic.

vs. Aquatic:
1. [npc=66950] > Wave > Geyser > Wave > pass (Pandaren dies).
2. select [npc=143053] > Powerball X2.
* last Powerball will hit the Magic.

vs. Magic
1. [npc=143053] > Powerball X 2 > Burrow. If needed > Powerball to finish the Magic.
2. Aquatic is back, [npc=143053] > Burst.
* both pets die and carry enters to get exp.

___________________________________________________________________________________

[npc=55367] (1,2,2)
[npc=85710] (2,1,2)
carry pet - with 500+ hp

1. [npc=55367] > Missile > Decoy > swap to [npc=85710].
2. [npc=85710] > Lovestruck (next round boss will swap pets) > Alpha Strike X3.
* the aqua pet dies, the elemental is back.
3. [npc=85710] > Predatory > Alpha Strike till the elemental is dead.
* enemy magic pet swaps in.
4. [npc=85710] > Lovestruck > Predatory. if your Lovebird is still alive, cast Alpha till it dies.
5. bring [npc=55367] > Decoy > cast Missiles till boss is below 540 > Explode.
* magic pet is dead and carry pet will enter for the exp.

good luck.

GL

One of the hardest, if not the hardest BFA pet trainer IMO. Much more so for the Family Battler achievement.
RNG-heavy because of the heal+critbuff and dark cyclone thingy. Prepare bandages.
I did it with these teams but it might be better to just do other trainers.

Humanoid

Spoiler

Squirky B/B 222
Anubisath Idol H/H 112
Flayer Youngling S/S 111

Start with Squirky
Bubble
Stampede
Fish Slap
Fish Slap (Lesser Charged Gale should die here)
Stampede until Squirky dies

Switch to Anubisath Idol
Sandstorm
Crush (Lesser Twisted Current should die here)
Rupture
Crush until Anubisath Idol dies

Switch to Flayer Youngling
Focus
Kick
Blitz until you win

Dragonkin

Spoiler

Nexus Whelpling P/B 122
Emmigosa P/S 212
Spawn of Onyxia P/S 111

Start with Nexus Whelpling
Arcane Storm
Mana Surge (Lesser Charged Gale should die here)
Arcane Storm
Tail Sweep until Nexus Whelpling dies

Switch to Emmigosa
Arcane Storm
Ice Tomb
Breath until Emmigosa dies

Switch to Spawn of Onyxia
Tail Sweep until you win

Note: feel free to skip Ice Tomb if it doesn't work for you. It's only good if it can hit Mind Warper

Flying

Spoiler

Crow S/B 222
Direbeak Hatchling H/P 121
Any level 25 Flying pet

Call Darkness
Nocturnal Strike
Alpha Strike
Alpha Strike
Alpha Strike (Lesser Charged Gale should die here)
Nocturnal Strike
Alpha Strike
Alpha Strike (Lesser Twisted Current should die here)

Crow dies, switch to Direbeak Hatchling
Ironskin
Falcosaur Swarm!
Predatory Strike
Falcosaur Swarm! until Direbeak Hatchling dies, finish with the other pet

Note: the first Nocturnal Strike is still 50% chance, just restart until it hits

Undead

Spoiler

Spectral Spinner P/S 122
Widget the Departed S/S 121
Scourged Whelpling P/S 222

Blinding Poison
Spectral Strike
Bone Bite until Spectral Spinner dies (Lesser Charged Gale should die at the same time or before)

Switch to Widget the Departed
Call Darkness
Spectral Strike
Pounce until Widget the Departed dies

Switch to Scourged Whelpling
Tail Sweep until you win

Critter

Spoiler

Rapana Whelk H/B 111
Glutted Bleeder 221 (no breed on my pet journal: 1319 hp 314 power 281 speed)
Alpine Chipmunk P/B 111

Acidic Goo
Dive
Ooze Touch until Lesser Charged Gale dies - or pass, see below
(VERY important to make sure Dive cooldown is 1 on your first turn vs Lesser Twisted Current)
Acidic Goo
Dive

Rapana Whelk dies, switch to Glutted Bleeder
Powerball
Dive (Lesser Twisted Current should die here, use Powerball once against it if it survives Dive)
Powerball
Burst

Switch to Alpine Chipmunk
Adrenaline Rush
Nut Barrage
Scratch until you win

Magic

Spoiler

Syd the Squid H/P 111
Minfernal H/H 222
Netherspace Abyssal P/S 221

Start with Syd the Squid
Bubble
Whirlpool
Water Jet
Water Jet (Lesser Charged Gale should die here)
Water Jet
Whirlpool
Water Jet until Syd the Squid dies

Switch to Minfernal
Extra Plating
Immolate (Lesser Twisted Current should die here)
Pass
Immolate
Explode

Switch to Netherspace Abyssal
Meteor Strike
Immolate

Note: very hard - this is the most reliable strategy I could come up with but it's still RNGish
Note: might be a lot easier with Baa'l, didn't include it because of how much effort is needed to get it

Elemental

Spoiler

Pandaren Water Spirit H/S 121
Core Hound Pup H/P 111
Fel Flame H/H 221

Whirlpool
Dive
Water Jet (Lesser Charged Gale MUST survive this)
Water Jet (Lesser Charged Gale dies here)
Water Jet
Whirlpool
Dive

Switch to Core Hound Pup
Howl
Scratch (Lesser Twisted Current dies here)

Switch to Fel Flame
Scorched Earth
Conflagrate
Flame Breath

Note: Core Hound Pup might be able to take Mind Warper's first attack if lucky

Beast

Spoiler

Kovok H/P 112
Black-Footed Fox Kit S/B 122
Zandalari Kneebiter P/B 222

Start with Kovok
Poison Fang
Puncture Wound
Pheromones

Kovok dies, Switch to Black-Footed Fox Kit
Bite until Lesser Charged Gale dies
Dazzling Dance
Howl
Bite until Black-footed Fox Kit dies

Switch to Zandalari Kneebiter
Bloodfang if Lesser Twisted Current is still alive, otherwise:
Black Claw
Hunting Party until you win

Note: any pet with Dazzling Dance and >301 speed works as second pet

Aquatic

Spoiler

Toothy P/S 121
Sandyback Crawler 222 (no breed on my pet journal: 1522 hp 321 power 240 speed)
Mongoose S/S 222

Start with Toothy
Rip
Blood in the Water
Surge (Lesser Charged Gale dies here)
Rip
Surge
Blood in the Water

Toothy dies, switch to Sandyback Crawler
Sandstorm (Lesser Twisted Current dies here)
Water Jet until Sandyback Crawler dies

Switch to Mongoose
Gnaw until you win, use Survival below 400ish hp

Mechanical

Spoiler

Iron Starlette P/B 111
Mechanical Pandaren Dragonling S/S 122
Any level 25 Mechanical pet

Powerball
Wind-Up
Powerball
Supercharge
Wind-Up
Powerball (Lesser Charged Gale dies here)
Wind-Up
Supercharge
Wind-Up (Lesser Twisted Current dies here)
Wind-Up
Wind-Up

Iron Starlette dies, switch to Mechanical Pandaren Dragonling
Breath until you win

Managed to do it with:
[npc=64633] - pump, pump, heal, pump, pump (first opponent's pet dies)
For second pet barely two pumps.

[npc=115787] - only managed to do Predatory strike.

[npc=64899] - Decoy, Thunderbolt, Breathe.

He managed to finish off the situation. There was no crits on my side. And I can't be certain this will work next time. Maybe I was just lucky this time.
Good Luck!

Edited 9/12/2018:
Also managed to do it with three hatchlings; Direbeak, Bloodgazer and Sharptalon: swarm and predatory strike as main attacks. I really find those hatchlings good in BFA for many other pet battles.
Good luck with Leana! ;)