>>35825769yeah, it was complete speculation on katara's part when she said that, and it was a good guess.
that's not to say that Korra didn't have a hard time with fire. She probably did. the opposite element still had to be challenging for them because the style of martial arts was different
Air = Ba Gua; circular, dodging movememts: have to be "light" on your feet
Earth = Hung Gar; rooted stances and strengthened strikes; solid stances and being unmovable
Water = Tai Chi; relaxed, flowing movements; Tai Chi is a martial art used to relax
Fire = Northern Shaolin; power and verocity is a must; not calm or relaxing.