Ruminas Valentine (Light Novel) vs Dorugoramon: who would win?

Dorugoramon favored — Slight edge (~55%)

Ruminas Valentine (Light Novel) · Tensei Shitara Slime Datta Ken · With Ultimate Skill

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Relativistic+, up to Speed Of Light

Durability

Low Complex Multiverse Level

Dorugoramon · Digimon · Dorugoramon

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Immeasurable

Durability

Low Complex Multiverse Level, up to Complex Multiverse Level

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