Remorhaz vs Maiko Plasma: who would win?

Maiko Plasma favored — Slight edge (~55%)

Remorhaz · Dungeons & Dragons · Base

Tier
9-A, up to 8-A
Attack Potency
Small Building Level+, up to Multi-City Block Level
Speed
Hypersonic+, up to Ftl+
Durability
Small Building Level+, up to Multi-City Block Level

Maiko Plasma · One-Punch Man · Base

Tier
8-C
Attack Potency
Building Level
Speed
Supersonic, up to Massively Hypersonic+
Durability
Unknown

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