Alfonse vs Kamen Rider Black RX: who would win?

Too close to call

Alfonse · Fire Emblem · Book I

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Superhuman, up to Massively Hypersonic+

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.