Yixuan vs Zenitsu Agatsuma: who would win?

Zenitsu Agatsuma favored — Slight edge (~55%)

Yixuan · Zenless Zone Zero · Base

Tier
7-C, up to HIGH 7-C
Attack Potency
Town Level, up to Large Town Level
Speed
High Hypersonic, up to Massively Hypersonic
Durability
Town Level, up to Large Town Level

Zenitsu Agatsuma · Demon Slayer · Post-Hashira Training

Tier
7-C
Attack Potency
Town Level
Speed
Massively Hypersonic+
Durability
Town Level

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.