Kamen Rider Mach vs Annihilarrgh: who would win?

Kamen Rider Mach favored — Favored (~65%)

Kamen Rider Mach · Kamen Rider · Dead Heat Mach

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Ftl

Durability

Wall Level

Annihilarrgh · Ben 10 · Base

Tier

1-C, up to 1-B

Attack Potency

Complex Multiverse Level, up to Hyperverse Level

Speed

Immobile, up to Immeasurable

Durability

Below Average Human Level

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