I saw Tsulong tamed and in a BG where he proceded to use his unlimited range aoe ability to spawn kill 40 horde players for over 20 minutes. The hunter had over 240 killing blows with 0 deaths before he left and went to orgrimmar…
My guess is blizz hotfixed away the ability to tame Tsu and others while they work on a fix.
P.S. i was not that hunter (srsly)
Haha, hunters have been reporting that pets are retaining their original abilities for months now (I think it also happened in BfA, it was just harder to trigger). There were videos of hunters using Ghostcrawler to massacre entire rooms in M+ on the beta using his armor-removing Nerfbat ability.
It’s all I needed to finish the mog
Xmog is my biggest beef with the current pet system atm. Like, I have a fire scorpid that goes with my transmog, that’s Ferocity/MS. I have a Rukhran, that’s Cunning/snare. But not a single one of the families for Tenacity/MS or Tenacity/snare matches my transmog. I eventually said screw it and settled for the feathermane that matches my order hall mount (though the fire turtle is also on the short list), the MS and snare really aren’t expected to be impactful enough anyway. But I hate that I’m tied down to such a tiny list of families for any given family combo.
Frankly, even the difference in number of families is silly. Ferocity/MS, Ferocity/snare, and Cunning/snare each have 5 families, 1 of which is Exotic. Ferocity/1m defensive and Ferocity/2m defensive both only have 2 families, 1 of which is also Exotic for each. So if MM or SV wants a Ferocity/defensive pet, they literally have two options: scalehides or gorillas. Scalehides have 17 skins across 4 models, and gorillas have 7 skins and one model. W 
T F
Lemme pick whatever the heck I want for me pet, yeesh.
Just do LFR and Normal.
Tamed double Eleons, on 25 normal, no issues at all. I just logged out for 30 minutes after each tame. Even killed the boss. Got the mount. Was so happy.
I’ve got him actually. It took 2 tries the first time I tamed him, but only once for the second tame on him.
Still can’t tame Tsulong on Normal, LFR or Heroic.
After failing to tame Tsulong last week on 25 heroic and LFR, I started with 10 man normal after the weekly reset. It worked for me then. The boss then respawned so people could clear the rest of the raid or tame another, if I were to guess. But I can confirm it works. Might not work for everyone, but it works for me. 10 man normal seems to be the common denominator for most.
after you tame the first time hearth out, go back to the vale and speak to dormi the person to turn the time back after that walk in side and queue up for the raid finder version. i got 2 elegons first week doing this.
For Elegon, you can also just use the unstuck functionality to die and port to the entrance, then log out or leave for 30 minutes to soft-reset it. That’s how I did it.
I tried on my Hunter, and got, “Not tameable”.
Having a few Hunter alts, I’ve managed to determine that both 25m Versions will end with “Target not Tamable”. I had not tried 10 Heroic, but 10 Normal was a successful Tame of Tsulong. So unless someone wants to risk their chance with 10m Heroic, just go in on 10m Normal.
To get Elegon (spirit breast / astral cloud serpent)… Go to Vale, Mogushan Palace. Talk to the NPC who sends you back in time outside the palace. Once you go back in time, go talk to Lorewalker Han ( Raid Finder Storyteller). You can do it in LFR and when done, leave group. It puts you back to Lorewalker Han in the past. You can just re-que and do it again if you want a second one.
has to be on normal which is weird but yea that worked
awesome that worked weeeeeeeeee
FYI, currently Elegon and the cloud serpents are bugged, their model is too large for them to beast cleave properly so be wary of using them in either of your pet slots. If I remember when I hear they fixed this I will repost back here. Or just check out the hunter discord if you would like.
I couldn’t tame Tsulong either. But I sure was able to get the Azure Serpent in the Shado Pan Monastery dungeon, on normal setting. Beautiful creature. Now I wish I could get Nalak (Isle of Thunder) and Huolon (Timeless Isle). Those two are constantly camped and get immediately killed every time they spawn. Bah humbug. 
Try going for those two with Warmode on. Huolon is almost permacamped on my server in regular mode but I went out there with WM on and the island was deserted with every named up and uncontested. Tried the same on Isle of Thunder and there was only one other hunter there who seemed to have gotten disconnected right as Nalak spawned.
That seems awfully complicated. I just ran through Mogushan Vaults and tamed Elegon when I got to him. Normal 10 man mode.