Aizono Mio vs Gwess: who would win?

Aizono Mio favored — Slight edge (~55%)

Aizono Mio · Toaru Majutsu no Index · Base

Tier

9-C, up to 8-C

Attack Potency

Street Level, up to Building Level

Speed

Transonic

Durability

Street Level, up to Building Level

Gwess · JoJo's Bizarre Adventure · Base

Tier

9-C, up to 9-B

Attack Potency

Street Level, up to Wall Level

Speed

Below Average Human, up to Average Human

Durability

Wall Level

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