He has no bending or even any fighting skills outside of bending. Azula however (though more in her sane state of mind) is skilled in bending, fighting without her bending, and is both clever and manipulative. Aside from Asami, Korra and her friends are easily distracted and wouldn't stand a chance against Azula and her brilliant mind and superb fighting abilities.

All the Avatar characters > all the Korra characters. Don't get me wrong I like LoK but all of the Avatar characters (minus a few like Cabbage man) could beat the Korra characters. Moreover Azula alone can take them all (well one on one or one on two...all at once would be a stretch). Likewise with say Zuko or Aang. But exactly answering the question; Azula and Ozai are a lethal duo I think they'd win easily.

Depends on whether or not Ozai and Azula would have their army backing them up or not. Ozai & Azula are skilled fighters to be sure, but 4 against 2 I believe the Krew would be able to defeat them.