Kopaka vs Demonic Fan: who would win?

Demonic Fan favored — Slight edge (~55%)

Kopaka · Bionicle · Toa Mata

Tier

7-B, up to HIGH 5-A

Attack Potency

City Level+, up to Brown Dwarf Level

Speed

Massively Hypersonic+, up to Relativistic

Durability

City Level+

Demonic Fan · One-Punch Man · Base

Tier

7-A

Attack Potency

Mountain Level

Speed

Massively Hypersonic

Durability

Unknown

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