Illidari Council down legit. Damage on me was pretty low tbh, I don't know why that is... I guess I just got more used to the mechanics and was able to avoid them better. Currently there is a bug so they go down to the health they had last time you wiped, so I had to oneshot this reset to get a legit kill.

The strategy I use is as follows:
Pull with misdirected Multi-Shots. Attack the Paladin (Gathios the Shatterer) mainly and have him tanked close to the two casters. Sometimes I send pet on Lady Malande (priest) to accomplish this, but also because it feels like she sometimes doesn't cast on me if she can melee my pet. Mage (High Nethermancer Zerevor) hits VERY hard so make sure to never get aggro on him, or at least Deterrence or FD if you do (can also send pet on him then, just like with Malande). Only use Silencing Shot to interrupt Malande's heals (Circle of Healing), never her damage spells. If she has Melee immunity up, don't waste it. In any case where the heal can't be interrupted, get Widow Venom up on the paladin (not sure whether this actually works or is worth it... could be it just reduces healing on HIM by 25% and therefore is only ~30k out of a total of ~500k healing combined).
Once the rogue (Veras Darkshadow) goes out of stealth, make sure to MD him to the pet and maybe hit him a little with the pet, since aggro on him will be reset.
I use Intervene when I get poisoned by the Rogue to absorb ticks as well as the next spell from Malande, and I use Feign Death to cancel out one of her spells. Be sure to cast Feign Death well before the cast is done, or it might go through anyway. Continue until they die or you do.

Video: World first hunter solo: Caribald vs Illidari Council - YouTube

Edit: Instructor Razuvious 25 man down.
Took me over 70 wipes to finally get it right. Since you can't Mind Control adds like on 10 man, they must be tanked by the pet while doing the Distracting Shot kiting as on 10-man. Jagged Knife does more initial damage and is cast more frequently (almost chain dotting you), so Chimera Shot only will not actually keep you up. The hardest part is damaging adds while kiting Razuvious without getting hit. Normally you would cast Distracting Shot at max range when Razuvious is not all the way at the pet yet, but to damage them you need to be closer, and you still need to keep Razuvious off your pet.
One thing I did was that every minute, Shell Shield + Cower would be up, so for the duration of those, the pet can actually tank. This is also useful for reapplying MD threat on the adds. I also marked each add so I could know the difference, and sometimes switch which one the pet was attacking. After getting adds down, the fight continues as on 10 man, except it's quite a lot longer and a single mistake can still cost the kill. You can barely keep up your hp by pet tanking every minute and doing an intervene, while spamming Chim Shot every time it's off cooldown. If you don't get melee hit by Razuvious when adds are up (or by an add for too long), hp shouldn't be a problem, but that's easier said than done

Video: World first solo (hunter): Caribald vs Instructor Razuvious (25 man) - YouTube

Edit: 10/15 Naxx 25! Four Horsemen just went down. It's all about finding the right tactic, and getting the first horseman down quick enough so pet can survive. I tank both Baron and Thane in between Zeliek and Blaumeux, so pet takes all 4 marks. I burn Thane and go in LoS of Zeliek to reduce pet damage. Once Thane dies, a pet switch soon becomes necessary. Even though a pet easily can go to crazy high stacks like 20+ with only one horseman left, with 3 up it can't go very far up. When switching pets, I Deterrence, wait for 7222 to stop while placing the pet same place as before, Feign Death and MD Baron. I kill Baron next, and during Baron another pet switch is probably needed. Since the damage is now much lower (about 4k+ dps less on pet), I can run out of range of Baron's mark and bandage. Everything stabilizes once Baron is tanked safely with the pet. Once he dies, I don't move the pet, because I need it to take both marks. Zeliek didn't want to nuke the pet when I showed myself, so killing him took longer than the others. With only Blaumeux left, I just sent pet in and she gladly shot the turtle instead of me
In short, find tactic, have enough dps and be good enough at keeping pet alive and switching them out, and they will die eventually.

Video: World first hunter solo: Caribald vs The Four Horsemen - YouTube

Edit: tee hee http://i.imgur.com/k1VLh.jpg

Edit: Gluth 25 down... although rather illegitimately. I managed to stop zombies from spawning (and as a result, no decimates either). How? I'm not entirely sure, but I basically reset the encounter by dismissing pet and then Feigning. The encounter doesn't completely reset right away; on the way back to his spawn point, he charged a zombie, and that's when I stood up and resummoned pet. I then got back in combat before a complete reset happened (or so I believe). It's basically similar to how you reset Naj'entus or Archavon 25, except I'm not sure if Gluth actually resets hp (he gets full by eating that zombie anyway though, so not like it matters). Then it's just a tank and spank really, once the -healing debuff gets too high you either wanna overaggro or dismiss -> summon new pet though, as it can't survive for long enough for the stack to go to 10 and then reset.
Edit: Actually, after rewatching it, he did go back to his spawn point completely and chilled there for a bit, but 4 zombies remained for a while. 3 of them disappeared, and Gluth charged the last one, and just then I went up. I'm pretty sure it's possible to do this consistently, because I've tried the same thing happening on 10 man when I tried to kill him as Survival.

Edit: Gluth 25 video: World first solo (hunter): Caribald vs Gluth (25 man) - YouTube

I wrote a blogpost with in-depth tactic on heroic Jaraxxus: Caribald, the hunter soloist: How to: Solo Lord Jaraxxus (heroic) as a hunter
... and uploaded heroic Northrend Beasts video: World first hunter solo: Caribald vs Northrend beasts (heroic) - YouTube
Blogpost coming later as I'm honestly too tired to write about it right now.

Sartharion +3 (10 man) on 40k... I ran too far away with Nitro boosts while he was casting a breath, didn't realize it before too late, then he went immune on 40k Gotta go now for the movies, hopefully can get a kill later!

Edit: Sarth 3D (10 man) down, Lord Marrowgar 25 normal down. Vids coming later.

Edit: Sarth 3D video rendering

Edit: Sarth 3D video up: World first hunter solo: Caribald vs Sartharion HM: The Twilight Zone - YouTube

Edit: I added a Northrend Beasts (heroic) guide on my blog: Caribald, the hunter soloist: How to: Solo Northrend Beasts (heroic) as a hunter

I can't get Marrowgar 25 footage in mp4 format for now, youtube claims it has 3rd party content even though I wasn't even listening to music lol... Converters usually make it look like crap. I found that VLC player apparently can do something called DirectStreamCopy a flv into mp4 without re-encoding, but I don't know how to do that yet.

Hmm, the last few resets I've done it with a friend cause I didn't wanna kick him if he wanted to tag along for the rest after Kalec, so my memory of those encounters might not be perfect. Eredar Twins are the hardest imo, and basically what I do is go Camo, place the turtle on low ground while standing on the ledge myself. I kill Sacrolash first. The positioning is done to maximize the distance the shadow adds have to travel (this is also the way it was done back at level 70), so they either hit you once or not at all. I've only experienced chain casting of Conflag if I had a friend with me, but not even always then (I guess my turtle had aggro when she chaincasted, because then there would be another possible target; I don't think it can be cast on the tank). When Sacrolash uses Confounding Blow she will run for you because it disorients your pet, and I think Alythess also shoots you with her Blaze, so you can't always be in the same position. Feigning will make them attack pet even though it's disoriented, but then it will not be ready for Conflag every time (it can of course can be done once followed by Readiness). Sadly I cleared Sunwell today with a friend so I can't even test things, but I could try and solo it next reset and share my findings. If you fall down from ledge, whether it's to get away from Sacrolash when she goes for you or whatever, just make sure to Intervene when ready, but basically you want to maximize distance so those shadow mobs can't hit you much.