The Sludgy and Pandaren earth spirit were pretty easy with Snarly and Baby ape (4,14).
Short version (which I guess is long enough):
Sludgy vs Baby ape
Flee until Sludgy is up first.
Start with Baby ape (smash, roar, barrel toss). First, charge up barrel toss. Then use Roar for the dmg buff. Then throw the barrel. This kills Sludgy outright with about 1800 dmg.
Baby ape has about 2-300 hp left, which means he soaks up both of the Earth spirit's stuns and putting them on CD. This also kills your Baby ape (if Earth spirit misses with his first stun, you get to hit him with a dmg-buffed smash).
Snarly vs Pandaren earth spirit
Next pet up is Snarly (rip, blood in the water, surge/water jet). He will kill the Earth spirit before his stuns are off CD. Start with rip, use blood in the water for massive dmg, then finish him off with surge / water jet.
Snarly will be killed by Darnak, but he gets a free attack as Darnak opens up with dmg reduction shield (reducing 80 inc dmg pr hit). Water jet hits hardest, but you only get to hit him once before Snarly dies by Burrow. Surge gets to hit twice because it always goes first, but it has lesser dmg than Water jet which is further mitigated by the dmg shield. Rip + surge can be an option, but the dmg shield does reduce the dot by 80 dmg pr tick. Not sure what's best but I have used both Water jet and Surge.
? vs Darnak
The two first pets are a pushover. Darnak is harder.
I used Clockwork gnome with metal fist (bonus vs beasts), repair and launch rocket (bonus vs beasts). At this point, Darnak has burrow on CD. He will stone rush you to death, which has a bonus vs mech so that makes Clockwork gnome unsuited and makes you dependendt on the RNG gods. Open up with launch rocket, then use launch rocket again (doesn't hit too hard, only about 800 dmg), then metal fist him to death (yuck). Darnak will use stone rush 2 or 3 times (can't remember, think it's 2 times), then use the dmg shield again. This means you need to metal fist him to death when he uses the dmg shield, because after that he will burrow and it's good night.
A critter might be best vs the stone rush.
Onyxian whelpling / Spawn of onyxia might be good too, as they aren't vulnerable to stone rush, have pretty decent hp, can heal 350+half of the stone rush dmg, and can use lift-off vs his burrow. Because of the dmg shield it might be best to opt with breath instead of tail sweep. I guess you start with breath, then use healing flame, then breath, then lift-off as Darnak's burrow is off CD, then rinse repeat. Think I used Onyxian whelpling the first time I killed him, but the second time around when I did the first daily he offered, I sort of forgot that because of rearranging my pet team for the other Pandarian spirit trainers (which were all pushovers).
Edit: I guess Darkmoon tonk might be best because of the nuke, like was said in an earlier post in this thread. Sadly, I haven't got this one until next darkmoon faire, and then have to level it up to 25 (which sucks now, because farmer nishi can't be used to powerlevel from 10-25 in about 7 pet fights with her).
I guess you could use Toothy instead of Snarly as Toothy has just as much attack, with just a little less hp and more speed. Haven't checked if Toothy (or one of the two other crocks) have sufficient speed to attack before the Earth spirit, in which case it could be a better solution to use those instead of Snarly).
- Start with Baby ape (smash, roar, barrel toss). Flee the battle until Sludgy comes up as the first opponent.
Open up with barrel toss to charge it up. Use roar to boost the damage (and to make the dmg boost last one round longer than if you opened up with roar the first round). Then barrel toss again to nuke down the sludge (he gets hit for like 1800 and dies).
- The next opponent is the Pandaren earth spirit. The Baby ape will have about 2-300 hp left.
Baby ape: The Earth spirit will spend his Crystal prison (no dmg), then Rupture (about 550 dmg, killing your Baby ape). If he misses with Crystal prison, you can get in a dmg-buffed hit with smash to soften him up some, although this is not necessary as Snarly will defeat him without problems. Note that you can of course use rake, but as the damage reduction won't save your Baby ape when the Earth spirit hits you with Rupture.
Snarly: Rip, Blood in the water, Surge / Water jet. You could use Water jet instead of surge, but I used surge to make sure I could get a hit in on Darnak before he kills Snarly. When Baby ape dies, the Earth spirit has both his stuns on CD. Open up with rip, then Blood in the water. Finish the Earth spirit off with Surge / Water jet. The Earth spirit won't have the opportunity to use the stuns on you before he dies.
- The last opponent is Darnak (the hardest one in my opinion, partly because I haven't got any pet at max lvl perfectly suited for defeating him).
Snarly: Darnak will open up with the damage reduction shield, allowing you one free hit. If you use Surge, you hit for low dmg because of the shield. Water jet hits for more. I'd say Water jet is best, although I'm not certain as of writing whether Rip is better because of the dot - he does mitigate 80 dmg from each hit thus negating the punch from dots.
If you choose Water jet, you will only get one hit in on him because he has higher speed than you. If you use Surge, you get two hits in. If you start with Rip then follow up with Surge, you get two hits in as well as a dot, but you might find that 2xSurge might be better than Rip+Surge because of the damage reduction.
Anyway, he will kill Snarly with Burrow, putting it on CD. He will then use Stone rush two times (or was it 3? this is where the pain comes in), and then he will rebuff himself with the damage reduction shield, granting you another free hit.
I used Clockwork gnome as my last pet, but this isn't optimal as Stone rush deals bonus damage vs mech. My Gnome used Metal fist (bonus vs beasts), Repair (not that you get to use it, perhaps if you use repair as your first move), and Launch rocket (bonus vs beasts). Opened up with Launch rocket, next round use it again to hit him pretty hard (although it's just about 800 dmg), then use Metal fist and pray to the RNG gods. Usually Darnak gets the upper hand with that pesky Stone Rush, but as long as you survive the two stone rushes - which you should be able to do, you HAVE to finish him off when he uses his damage shield again. After that he will Burrow, rendering you doomed.
A critter might do well because of reduced dmg from Stone rush.
Perhaps Onyxian whelpling / Spawn of onyxia might do well with Deep breath / Lift-off and Tail sweep and as they should survive the Stone rushes and can use the heal to heal back 350+half the incoming dmg.