Zen'ō vs Kamen Rider Black RX: who would win?

Zen'ō favored — Slight edge (~55%)

Zen'ō · Dragon Ball · Base

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Massively Ftl+

Durability

Complex Multiverse Level

Kamen Rider Black RX · Kamen Rider · End of Series (41-47)

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Transonic, up to Immeasurable

Durability

Complex Multiverse Level

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