The following table lists the best pets that I currently own to use in various daily combats, at least that I've found so far. Some of the combats I can start with a level 1 in the first position, survive a round, and then finish up with the remaining 2 pets. Other combats I can put a lowbie in later (for example, when sandstorm is up on Glowy). This can advance a level 1 pet extremely fast (2 battles to level 10!).

The table will be updated as I accumulate additional level 25 blue pets.

Opponent	Zone	Pet 1		Pet 2		Pet 3
Farmer Nishi	Valley of Four Winds	[Siren] (elemental)		[Toothbreaker] (elemental)		[Brood of Mothra] (beast)
		[Eternal Strider] (aquatic)	Water Jet Cleansing Rain Pump	[Wanderer's Festival Hatchling] (aquatic)	Grasp Shell Shield Pump	[Rabid Nut Varmint] (mechanical)	Metal Fist Extra Plating Repair
Wastewalker Shu	Dread Wastes (Klaxxi'vess)	[Crusher] (aquatic)		[Pounder] (elemental)		[Mutilator] (beast)
		[Eternal Strider] (aquatic)	Water Jet Cleansing Rain Pump	[Wildhammer Gryphon Hatchling] (flying)	Peck Slicing Wind Lift-off	[Rabid Nut Varmint] (mechanical)	Metal Fist Extra Plating Repair
Lydia Accoste	Karazhan	[Jack] (elemental)		[Bishibosh] (undead)		[Nightstalker] (undead)
		[Bandicoon] (critter)	Tongue Lash Counterstrike Powerball	[Bandicoon Kit] (critter)	Tongue Lash Counterstrike Powerball
		Lead of with random low level pet. Jack normally casts a defensive ability first, but quit and retry if he poisons or kills lowbie. Then use Powerball to kill Jack and Tongue Lash to kill the others. Level 1 lowbie goes to level 8.
Stone Cold Trixxy	Winterspring	[Tinygos] (dragonkin)		[Frostmaw] (beast)		[Blizzy] (flying)
		[Kun-Lai Runt] (humanoid)	Takedown Mangle Rampage	[Nordrassil Wisp] (magic)	Light Flash Arcane Explosion
		Lead of with random lowbie. He might get hit but never poisoned. If you use the same low level pet you used against Lydia and it won't be killed (and will go from level 8 to 11). Swap in Kun-Lai Runt. Kill Tinygos with Takedown and Frostmaw with Rampage Swap in Nordrassil Wisp for Blizzy. Use Flash followed by Light, then if necessary use Arcane Explosion as necessary.
Bloodknight Antari	Shadowmoon Valley	[Arcanus] (magic)		[Jadefire] (elemental)		[Netherbite] (dragonkin)
		[Wild Crimson Hatchling] (dragonkin)	Tail Sweep Healing Flame Deep Breath	[Eternal Strider] (aquatic)	Water Jet Cleansing Rain Pump	[Kun-Lai Runt] (humanoid)	Takedown Mangle Rampage
Burning Pandaren Spirit	Townlong Steppes	[Crimson] (dragonkin)		[Pandaren Fire Spirit] (elemental)		[Glowy] (flying)
		[Anubisath Idol] (humanoid)	Crush Sandstorm Deflection	[Rapana Whelk] (critter)	Absorb Acidic Goo Dive
		Anubisath Idol can solo for the most part. Against Crimson, start with Crush, then Sandstorm, then Deflection.This lines up perfectly with his first 3 attacks. Then Crush until he's dead Next, against Pandaren Fire Spirit, use immediately. Then Crush until he's dead, renewing Sandstorm as necessary. Finally against Glowy, make sure Sandstorm is up. Then you can swap in random lowbie pet number 3 for a round so he gets a crapload of experience.Then put back Anubisath idol and Crush until he's dead, renewing Sandstorm as necessary.
Whispering Pandaren Spirit	Jade Forest	[Dusty] (critter)		[Whispertail] (dragonkin)		[Pandaren Air Spirit] (elemental)
		[Emerald Proto-Whelp] (dragonkin)	Breath Ancient Blessing Proto-Strike	[Azure Whelpling] (dragonkin)	Claw Wild Magic Surge of Power	[Wild Crimson Hatchling] (dragonkin)	Tail Sweep Healing Flame Deep Breath
		RNG on Proto-Strike plays a really big factor here. Timing vs. Dusty's attacks is crucial as he can block or interrupt it. Sometimes Protodrake wins by himself. Other times it comes down to the end.
Sully "The Pickle" McLeary	Celestial Tournament	[Socks] (undead)		[Monte] (critter)		[Rikki] (aquatic)
		[Spiny Terrapin] (aquatic)	Grasp Shell Shield Powerball	[Razzashi Hatchling] (beast)	Bite Leap Devour	[Jade Owl] (magic)	Slicing Wind Adrenalin Rush Lift-Off
		Softshell Snapling can replace Spiny Terrapin, and any of the Raptor Hatchlings can go second. This can make multiple tries viable if necessary
Phase 1	Wailing Caverns
		[Teroclaw Hatchling] (undefined)	Nature's Ward Dodge Alpha Strike
		Keep Nature's Ward up at all times Use Dodge on cooldown Alpha Strike as filler.
Phase 2	Wailing Caverns	[Son of Skum] (undefined)
		[Zandalari AnkleRender] (undefined)	Black Claw Primal Cry Hunting Party	[Anubisath Idol] (undefined)		[Emerald Proto-Whelp] (undefined)
		Black Claw, Hunting Party, Primal Cry. Skum dead.

The ideal pets for a lot of the tougher fights are those that take reduced damage because of their types, but also have an attack that will do extra damage.

If opponent is:	Use:	Example:
Aquatic doing Aquatic damage	Magic doing Flying damage
Aquatic doing Beast damage	Flying doing Flying damage	Dragonbone Hatchling
Aquatic doing Critter damage	Humanoid doing Flying damage
Aquatic doing Dragonkin damage	Undead doing Flying damage
Aquatic doing Elemental damage	Critter doing Flying damage
Aquatic doing Flying damage	Dragonkin doing Flying damage	Wild Crimson Hatchling
Aquatic doing Humanoid damage	Beast doing Flying damage
Aquatic doing Magic damage	Mechanical doing Flying damage
Aquatic doing Mechanical damage	Elemental doing Flying damage
Aquatic doing Undead damage	Aquatic doing Flying damage
Beast doing Aquatic damage	Magic doing Mechanical damage
Beast doing Beast damage	Flying doing Mechanical damage
Beast doing Critter damage	Humanoid doing Mechanical damage
Beast doing Dragonkin damage	Undead doing Mechanical damage
Beast doing Elemental damage	Critter doing Mechanical damage
Beast doing Flying damage	Dragonkin doing Mechanical damage
Beast doing Humanoid damage	Beast doing Mechanical damage
Beast doing Magic damage	Mechanical doing Mechanical damage	Rabid Nut Varmint 5000
Beast doing Mechanical damage	Elemental doing Mechanical damage
Beast doing Undead damage	Aquatic doing Mechanical damage
Critter doing Aquatic damage	Magic doing Beast damage
Critter doing Beast damage	Flying doing Beast damage
Critter doing Critter damage	Humanoid doing Beast damage	Kun-Lai Runt
Critter doing Dragonkin damage	Undead doing Beast damage
Critter doing Elemental damage	Critter doing Beast damage
Critter doing Flying damage	Dragonkin doing Beast damage
Critter doing Humanoid damage	Beast doing Beast damage	Crystal Spider
Critter doing Magic damage	Mechanical doing Beast damage
Critter doing Mechanical damage	Elemental doing Beast damage	Crimson Shale Hatchling
Critter doing Undead damage	Aquatic doing Beast damage	Softshell Snapling
Dragonkin doing Aquatic damage	Magic doing Humanoid damage
Dragonkin doing Beast damage	Flying doing Humanoid damage
Dragonkin doing Critter damage	Humanoid doing Humanoid damage	Kun-Lai Runt
Dragonkin doing Dragonkin damage	Undead doing Humanoid damage
Dragonkin doing Elemental damage	Critter doing Humanoid damage
Dragonkin doing Flying damage	Dragonkin doing Humanoid damage
Dragonkin doing Humanoid damage	Beast doing Humanoid damage
Dragonkin doing Magic damage	Mechanical doing Humanoid damage
Dragonkin doing Mechanical damage	Elemental doing Humanoid damage
Dragonkin doing Undead damage	Aquatic doing Humanoid damage
Elemental doing Aquatic damage	Magic doing Aquatic damage
Elemental doing Beast damage	Flying doing Aquatic damage
Elemental doing Critter damage	Humanoid doing Aquatic damage
Elemental doing Dragonkin damage	Undead doing Aquatic damage
Elemental doing Elemental damage	Critter doing Aquatic damage
Elemental doing Flying damage	Dragonkin doing Aquatic damage
Elemental doing Humanoid damage	Beast doing Aquatic damage
Elemental doing Magic damage	Mechanical doing Aquatic damage
Elemental doing Mechanical damage	Elemental doing Aquatic damage
Elemental doing Undead damage	Aquatic doing Aquatic damage	Eternal Strider
Flying doing Aquatic damage	Magic doing Magic damage	Nordrassil Wisp
Flying doing Beast damage	Flying doing Magic damage
Flying doing Critter damage	Humanoid doing Magic damage
Flying doing Dragonkin damage	Undead doing Magic damage
Flying doing Elemental damage	Critter doing Magic damage
Flying doing Flying damage	Dragonkin doing Magic damage
Flying doing Humanoid damage	Beast doing Magic damage
Flying doing Magic damage	Mechanical doing Magic damage
Flying doing Mechanical damage	Elemental doing Magic damage
Flying doing Undead damage	Aquatic doing Magic damage
Humanoid doing Aquatic damage	Magic doing Undead damage
Humanoid doing Beast damage	Flying doing Undead damage
Humanoid doing Critter damage	Humanoid doing Undead damage
Humanoid doing Dragonkin damage	Undead doing Undead damage
Humanoid doing Elemental damage	Critter doing Undead damage
Humanoid doing Flying damage	Dragonkin doing Undead damage
Humanoid doing Humanoid damage	Beast doing Undead damage
Humanoid doing Magic damage	Mechanical doing Undead damage
Humanoid doing Mechanical damage	Elemental doing Undead damage
Humanoid doing Undead damage	Aquatic doing Undead damage
Magic doing Aquatic damage	Magic doing Dragonkin damage
Magic doing Beast damage	Flying doing Dragonkin damage
Magic doing Critter damage	Humanoid doing Dragonkin damage
Magic doing Dragonkin damage	Undead doing Dragonkin damage
Magic doing Elemental damage	Critter doing Dragonkin damage
Magic doing Flying damage	Dragonkin doing Dragonkin damage
Magic doing Humanoid damage	Beast doing Dragonkin damage
Magic doing Magic damage	Mechanical doing Dragonkin damage
Magic doing Mechanical damage	Elemental doing Dragonkin damage
Magic doing Undead damage	Aquatic doing Dragonkin damage
Mechanical doing Aquatic damage	Magic doing Elemental damage
Mechanical doing Beast damage	Flying doing Elemental damage
Mechanical doing Critter damage	Humanoid doing Elemental damage
Mechanical doing Dragonkin damage	Undead doing Elemental damage
Mechanical doing Elemental damage	Critter doing Elemental damage
Mechanical doing Flying damage	Dragonkin doing Elemental damage
Mechanical doing Humanoid damage	Beast doing Elemental damage
Mechanical doing Magic damage	Mechanical doing Elemental damage
Mechanical doing Mechanical damage	Elemental doing Elemental damage	Crimson Shale Hatchling
Mechanical doing Undead damage	Aquatic doing Elemental damage
Undead doing Aquatic damage	Magic doing Critter damage
Undead doing Beast damage	Flying doing Critter damage
Undead doing Critter damage	Humanoid doing Critter damage
Undead doing Dragonkin damage	Undead doing Critter damage
Undead doing Elemental damage	Critter doing Critter damage	Bandicoon
Undead doing Flying damage	Dragonkin doing Critter damage
Undead doing Humanoid damage	Beast doing Critter damage
Undead doing Magic damage	Mechanical doing Critter damage
Undead doing Mechanical damage	Elemental doing Critter damage
Undead doing Undead damage	Aquatic doing Critter damage