As a ToC / ICC geared Protection Paladin I've managed to solo every boss in BWL except for the first two, I bring a Resto / Feral Druid for these.
For Razorgore (2-Man) I simply tank the room while my Druid friend destroys all the eggs
For Vael (2-Man) I spec Ret, the Druid specs Feral and we burn, if I get the Adrenaline, I die, get a battle rez and keep going. If the Druid gets Adrenaline we run out of BWL and I rez him, or simply DI. Its basically just RNG.
The only other real challenge is Chromaggus, if he has Time Lapse it's almost impossible to beat him in the conventional way. But if do it correctly you can now LoS it by positioning him in the doorway between Flamegor and Chrommy, and then moving behind the wall when he does a breath.