when the "elite" pets were introduced in patch 5.2, they were pretty much a joke. i slapped together three beast-damage pets for killing the elite critters, three mechanical pets for the beasts, and three flyers for the aquatics. almost no thought at all, and the beasts of fable were on farm. yawn. the only hard part was the time required to travel to all ten.
yesterday, patch 5.3 made some changes. instead of one quest to kill all ten, there are now three quests, each of which gives the same reward as the original. so you can choose how much time to invest versus how much reward. yay on that.
but the pets themselves were also changed. they have only half as much health, but all incoming damage is cut in half. (their power may also have been increased a bit, but i'm not sure and it's hard to check). for many of the pets this has no net effect - still takes the same amount of damage to kill them. for those that can heal themselves, however, the impact is huge, since the amount of healing was not halved. killing these guys - nitun and dos-ryaga - is now a lo harder. not surprisingly, the official pet battle forum erupted with cries of "it's impossible!" and "gg blizz" and "that's it i'm gonna cancel my account."
but of course, it isn't impossible, as the second wave of posters on the forum pointed out. you just need to make sure your teams are prepared for what they'll be facing. for dos-ryaga it turned out i was already set - i've always sent in my crow first and opened with call darkness (followed by nocturnal strike), and that messed up his healing enough that i didn't notice the difference. nitun, though, he gave me fits for a while. other than trouble the kun-lai runt, my team wasn't damaging him enough to overcome the healing he got when he killed them. so i ultimately brought in the duck of death and my brilliant kaliri - both flyers so his beast attacks were weakened. beast damage, speed bonuses, and predatory strike to finish him off. i'm sure there's more ways to skin this raccoon (the post that said the undead racial bonus negates his healing ability has me intrigued) and i'll try at least a few more of them. what's important to remember is, these battles are puzzles. if your first plan doesn' work, take a step back and try something different. enough thinking and patience, and you'll find a solution.