Bark the Polar Bear vs King Dark: who would win?

King Dark favored — Slight edge (~55%)

Bark the Polar Bear · Sonic · Base

Tier

HIGH 5-A

Attack Potency

Brown Dwarf Level

Speed

Ftl

Durability

Brown Dwarf Level, up to Complex Multiverse Level

King Dark · Kamen Rider · Base

Tier

LOW 4-C

Attack Potency

Small Star Level

Speed

Superhuman, up to Speed Of Light

Durability

Small Star Level

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