As always, spoiler break starts immediately. Don’t read if you don’t want to be spoiled for Season 4 of Legend of Korra.
No, Azula doesn’t really count. She was just a small cog in Firelord Ozai’s bigger plans, who was the true antagonist in Season 3 of the original series.
Kuvira’s motivation for turning against Suyin sounds a bit strange. Inaction on Suyin’s part, that would eventually spur Kuvira to become a conqueror and enslaver?
Still, I am happy to see a female villain, and everything is being set up for an all-ladies showdown between Korra and Kuvira. Nickelodeon, if you can make this a PROPER duel with NO interference from Jinora (again), you are on the verge of turning Legend of Korra Season 4 into the Nick version of Kill la Kill.
Do it right, and let this series end on the highest note possible. With lasers, mecha tanks, and wrestling moves.