Niuzao at the least is soloable.
http://www.youtube.com/watch?v=yjmVsIpXrsI
It's one of the easier pets to get on the islands, in my experience. Just park an alt up there and keep track of the respawn timer. Takes a while, but you can do other things while you wait (like fishing up a carp for yourself in the lake).
Diplomacy is just war by other means.
Farmed mine, took well over 30 kills before I finally got the damn thing. Personally, if you don't want it, then sell it. If you want it, keep it. That's all it comes down to.
Fenixdown (retail) : level 60 priest. 2005-2015, 2022-???? (returned!)
Fenixdown (classic) : level 70 priest. 2019 - present
The celestials aren't hard to solo, they just take ages. If you go there RIGHT NOW with a chi'ji buff I'm sure you will get to 80% no problems. The hardest part of soloing them is not having people help you as a tank.
But please, say I'm full of crap before even going to youtube.
http://www.youtube.com/results?searc...+warcraft&sm=3
http://www.youtube.com/results?searc...+warcraft&sm=3
Yu'lon and Xuen are harder to find but if you have a look around these forums you will find plenty of people who have tested it.
Vasuvius damage is easy to outheal from my impressions doing it solo to 60% before others joined, is there something I'm missing?
Archerieus only have 26m hp iirc so if you pop cd's with the chi'ji buff they melt fairly fast. I struggle against high priests (same move set) without cd's though due to the nature of golems + fire cones making it very hard to melee. Much preference to being a warlock/hunter here if you have one.