Remember when Toph instigated Aang to get into the avatar state?

Lol, the first 2 seasons both were water bender villains.

I like that in Korra, the main villain was our first airbender villain, at lease if you can consider that an airbender with the spirit portal somehow gifting a whole new generation of humans wind powers, rather than natural born wind benders.

So we got water bender villain, airbender villain, and earth bender villain. To contrast with the avatar's fire nation all being the villains. That was one of the good things about Korra, it explored all new avenues and contrasted perfectly with Avatar.