Sardonyx vs Gun Devil: who would win?

Sardonyx favored — Slight edge (~55%)

Sardonyx · Steven Universe · Base

Tier

HIGH 7-C

Attack Potency

Large Town Level

Speed

Relativistic

Durability

Large Town Level

Gun Devil · Chainsaw Man · 100% Gun Devil

Tier

HIGH 7-C, up to 7-B

Attack Potency

Large Town Level, up to City Level

Speed

Massively Hypersonic, up to Sub-Relativistic

Durability

Large Town Level

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