Avatar Aang runs the Dragon Ball World Gauntlet

[SIAD]

What is the least powerful character in DB capable of defeating Avatar Aang?

 

[Captain Cadaver]

Aang at his peak would receive City level scaling from past Avatars such as Kiyoshi separating a small island or another Avatar causing a volcanic eruption and would have Massively Hypersonic speed and reactions from characters like Zuko being able to catch lightning. The weakest character to prove a match for him would be possibly Popo, though it's more likely Kami would be needed to defeat Aang.