system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA] Is Air Bending allowed in pro-bending matches?
gpt
As it exists at the start of Legend of Korra, the rules are hard-coded that each team gets an earth bender, a fire bender and a water bender. There is no valid position for an airbender, because the rules were written on the assumption that one wouldn't be available for all teams, and letting the few teams that could find one have one would be tantamount to cheating. 

This is reflected in how Korra is forced to play; she's playing in the water bender position, so she's only allowed to use water bending. Even when she does get her airbending down, using it would be a giant foul, as would swapping to fire or earth.

It's possible that after the convergence, there could be a four-man variant introduced.