Kazumi vs Billy Alfred: who would win?

Billy Alfred favored — Favored (~65%)

Kazumi · Puella Magi Verse · Real Magical Girl

Tier
6-C, up to 5-C
Attack Potency
City Level, up to Moon Level
Speed
Massively Hypersonic, up to Massively Hypersonic+
Durability
City Level, up to Mountain Level

Billy Alfred · Undead Unluck · 101st Loop

Tier
HIGH 7-A
Attack Potency
Large Mountain Level
Speed
Ftl+
Durability
Large Mountain Level

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