Kamen Rider X vs Marluxia: who would win?

Marluxia favored — Favored (~65%)

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

Marluxia · Kingdom Hearts · Kingdom Hearts III

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Infinite

Durability

Multiverse Level, up to Complex Multiverse Level

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