Alastor vs Undodog: who would win?

Too close to call

Alastor · Hazbin Hotel · Base

Tier
LOW 7-C
Attack Potency
Small Town Level
Speed
Subsonic, up to Supersonic+
Durability
Building Level, up to City Block Level+

Undodog · Super Mario Bros · Base

Tier
LOW 7-C
Attack Potency
Small Town Level
Speed
Unknown
Durability
Unknown

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