I like Azumas attacks though, I guess through all the manga he was just taking it easy on most enemies or just being lazy since he took out one of Kakuzu's hearts with just 1 wind attack.

I was under the impression that it was Azuma who did the wind attack that took out the lightning monster?

It was Asuma, and unless Im reading it wrong, dont forget that Wind > Lighting, Asuma used a high level wind attack to take out the lightning dude. So yeah thats why it was a 1-hit.

EDIT: Quote Fail but whatever you get the point