Annihilarrgh vs Kamen Rider X: who would win?

Kamen Rider X favored — Favored (~65%)

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

Kamen Rider X · Kamen Rider · Skyrider, Super-1 & ZX

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

High Hypersonic, up to Ftl+

Durability

Multi-City Block Level, up to Complex Multiverse Level

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