All Bending Arts in ATLA contain defensive and offensive moves:
When Aang fights with Hi De, On Ji’s boyfriend, he defends himself using Ba Gua Zhang i.e. Wu Dang style martial arts. This style is famous for its ‘circle walking’ i.e. avoiding the opponents strikes by staying behind their back. Aang demonstrates it rather well in the gifs.
Baguazhang practitioners are known for their ability to “flow” in and out of the way of objects. … Baguazhang’s evasive nature is also shown by the practice of moving behind an attacker, so that the opponent cannot harm the practitioner.
These flowing movements can be seen in airbending, but also in Aang’s fighting style. Further it is a reference to the avoidant part of Aang’s character and his element i.e. like air that flows around an obstacle, Aang prefers to find another way, instead of facing the problem head on.
Airball and Firebending
The poles we see are not used in bagua zhuang, but in gongfu. Why is this interesting? Because firebending is based on Shaolin gongfu.
Those who practice Shaolinquan leap about with strength and force; people not proficient at this kind of training soon lose their breath and are exhausted.
Of the multitude styles of kung fu and wushu, only some are actually related to Shaolin. Aside from a few very well known systems, such as Xiao Hong Quan, the Da Hong Quan, Yin Shou Gun, Damo Sword, etc. after the loss of records during the 20th Century Cultural Revolution it would be almost impossible for a particular style to conclusively establish a connection to the Temple.
I find the last sentence interesting, since both, Fire Nation Firebending and Gongfu have lost their connection to their source.
Now what could that mean?
What we have here is an overlap in martial arts styles in the bending arts.
Well, a simple explanation would be a goof, but if you want you could read deeper meaning into it: The overlap between bending Uncle mentions (Him learning from the waterbenders) and the deeper interconnection between the elements.