1. The combination of challenge tames and track-tracing. Fun fun!
2. The mechanic that you can't tame a certain rare without getting a hint from an NPC first.
3. More "scripted" rare events.
4. Rares that require an item or object to tame.
Why?
1. To offset shortened spawn timers with Pandaria rares, some creatures should be a real challenge to find and obtain!
2. To obey certain lore, or just to make rares feel more unique.
3. Again, to make certain rares feel more unique and give them an interesting "mini-quest."
4. To increase the difficulty of tames, or make them something to work towards like Alani.
Quetzlcoatl
<Terror of the Skies>
Tracking: Tracked like any other current Pandaria rare. The "clues" are called Flattened Leaves.
When caught with a flare, the NPC leaving behind the tracks will actually turn out to be a dead raptor. What a twist! You may say. For when this happens, after one or two seconds a massive pterrorwing will aggro and fly out of the sky to attack you. After all, you're messing with his kill!
Taming: Quetzlcoatl requires a "challenge" to tame. You have to lower the beast's health significantly before taming him. He has two special abilities: a flurry of attacks that cannot be interrupted, and a forward smash that must be dodged. When Quetzlcoatl is at 30% health, he can be tamed (but be warned: the pterrorwing is immune to traps!)

The area where Quetzlcoatl can be found.
Thunderclaw
<The Sneaky Mushan>
Tracking: To track Thunderclaw, you must first talk to a Stoneplow Farmer. After completing the Stoneplow questline, one of these NPCs has a chance to say the following quote:
After this has been done, you might be able to find Faint Tracks: http://i.imgur.com/P0vBcxq.pngThe mantid threat has lessened for now, but my mushan beast has run off again! How does a creature that size -- and one named Thunderclaw, nonetheless, manage to sneak off every few days? Tell you what... if you find him, you can keep him! I've got better things to do than babysit a mushan all the time.
Successfully following the trail and using a flare at the correct time will lead you to Thunderclaw, who can be tamed as normal.

Thunderclaw's (rather quiet) stomping grounds.
Rovok
Tracking: Before you track this behemoth, you must reach at least Honored reputation with the Klaxxi and have freed the paragon Kaz'tik the Manipulator. After you turn in a daily to him, the mantid has a chance to say:
After obtaining this clue, you might be able to stumble across Heavy Clawprints in the surrounding area around Klaxxi'vess: http://images.wowhuntershall.com/2012/0 ... Tracks.jpg Following these tracks to their end will lead you to a Fresh Amberscale Carcass, a dead Amberscale Basilisk with a bloodstain underneath it.Kovok was not my only domesticated kunchong, you know. Before I was encased in amber, I had begun to take care of another... she always loved to devour tasty mushan flanks.
But not so fast! You'll need more than clever eyes to draw out this reclusive kunchong. You'll need to gather 5 [Tasty Mushan Flank], roughly a 10% droprate from Greatback Mushan, and combine them into a [Tasty Mushan Bait]. Once you've discovered the basilisk carcass, you'll right-click to place down a hunk of the meat.
After a few seconds, Rovok will emerge!
Taming: Nothing super-special here, but she will often knock you back while channeling the tame and use a one-shot ability, Devastating Arc, that you must run behind.

One of the locations where the mantid tank can be found.
Zarikk
<Stalker of the Sands>
Tracking: You must first complete the Thunderdrome questline in Gadgetzan. Beating the final boss of Thunderdrome: Grudge Match will then change Dr. Dealwell's dialogue to the following.
This will then unlock the rare spawn Gilligan the Tracker, a friendly goblin NPC.Hey, hey, <player name>! You did good in there! Looking for more things to fight? We've got one of our best goblins working to capture another silithid now... maybe you can track him down.
He can spawn in a number of different locations around either of the two hives in the zone.
Talking to Gilligan will result in the following RP sequence:
Gilligan pokes the slightly shifting sand with his spear.Aha, reinforcements have arrived! Be careful, <player name>: after C'thun was killed, all sorts of nasty bugs spilled out into the surrounding areas. I think I'm pretty close to capturing one now!
A furious sandreaver bursts out of the ground!Here goes nothi-

The goblin's final moments.
Taming: Gilligan is killed as soon as Zarikk emerges. You must then subdue the sandreaver before taming him. The creature has roughly 1.3 million health and is boss level, meant to mirror the sandreavers of the Ahn'Qiraj raids.
Zarikk has three main abilities: a burrow that makes him immune to attack, a tail swipe that knocks you into the air (high enough to deal falling damage), and the Sand Trap ability. For those who don't know, existing sandreavers in the game spit out these piles of sand, which will activate when touched. Zarikk's Sand Traps will stun you for 2 seconds, and silence you for 8. These are the key to the fight: you must lead the reaver into his own traps, which deal 5% of his total health each time. The stun lasts for only 2 seconds on him.
When he reaches 20% health, his special "untameable" buff is removed. The next trap he hits is intended to be the time for you to cast Tame Beast, and hope you don't die!
Escaped Ji-Kun Fledgling
Tracking: The fledgling leaves behind Shed Feather tracks, which look like a single feather on the ground. You can find these just outside the Throne of Thunder, on the beach. Flaring the beast out successfully will start the challenge tame.

The beach where the young bird has flown.
Taming: Like most of these other new rares, the fledgling's will must be broken before she is tamed. To do this, you must bring her to low health. The fight is a lot like Razorscale of Ulduar.
Nearby, a rather convenient Mogu Harpoon-Gun lies unused, perhaps created ages ago to combat a threat from the sea. You must use this harpoon gun to spear the Ji-Kun Fledgling and bring her to the ground, where you can damage her. After a while, the bird will break free from the harpoon's chain and fly around. At this stage she is mostly out of range of your ranged attacks.
The fledgling has two special attacks: Pool of Goo and Ear-Shattering Shriek. The pools of goo are dropped from the fledgling every few seconds when she flies around and must be avoided, otherwise standing in them inflicts serious damage. The Ear-Shattering Shriek is cast every 20 seconds or so, and must be interrupted or you'll instantly die.
Once the fledgling is at 30% health, she can be tamed with a bit of luck.
Rebellious Silentstrike Pterrorwing
(Armored versions of the above skins)
Location: Perhaps the first multi-zone rare! (?) She paths all around Pandaria, passing over all possible spawn locations of the Zandalari Warbringers.Tracking: Much like a non-despawning TLPD, you can either pick a spot and camp it or fly all around her path, hoping to find the RSP. Note that this pterrorwing flies at roughly 340% flight speed, so you'll have to cut off her path and take a shortcut in order to catch up.

On her path, exiting the jungles of Krasarang.
Taming: This beast resisted the Zandalari, and your trying to tame her will be no different! This will certainly be a challenge...
Phase 1: Jump on her back. Sound familiar? During this phase, you'll deal damage to her while avoiding her multiple attacks...
[Buck] - The pterrorwing attempts to knock you off her back. 5 second cast time, and 100% success rate. Must be interrupted.
[Rock and Roll] - The pterrorwing rocks back and forth and then dives into an airborne roll. A few seconds before this ability is used, a small button Hold Tight appears. You've gotta click it, or you will certainly fall to your death!
Piercing Cry - Uninterruptable. Nothing you can do about this except hope she doesn't cast it too often.
Phase 2: After losing about 2-3 m out of her total 8, the pterrorwing will land. Now she gains a new set of abilities.
Piercing Cry remains, so be on your toes to try and avoid it.
[Deafening Screech] - Stuns you for two seconds. Cannot be interrupted.
[Dazing Screech] - "Confuses" the player for five seconds. 5 seconds after using this ability, she will...
[Silent Strike] - A very quick 1-second cast, and an AoE that deals 90% max health damage to anything in front of it. She always targets the player with this attack.
[Vicious Claw] - A weak melee that causes a nasty bleed effect.
After Phase 2, at roughly 1/8m health, she gains one last ability:
[Desperate Charge] - Charges forward, instantly killing the target.
You must dodge this attack, and after an unsuccessful charge she will be stunned for 10 seconds. Now's when you tame the beast!
To summarize the fight, you...
Jump on her back, avoid being knocked off. DPS her down when she lands, and get out of the way as soon as your "confuse" effect wears out! Bring a spirit beast or a pet with Spirit Bond to deal with her bleeds. Then dodge a charge or two and tame.
Let me know your thoughts on these ideas! Post your own!