Tarmiel vs Cosmic Owl: who would win?

Tarmiel favored — Slight edge (~55%)

Tarmiel · Nanatsu no Taizai · Possessing Arbus

Tier

4-B

Attack Potency

Solar System Level

Speed

Relativistic

Durability

Unknown

Cosmic Owl · Adventure Time · Base

Tier

HIGH 4-C, up to 3-C

Attack Potency

Large Star Level, up to Galaxy Level

Speed

Massively Ftl+

Durability

Large Star Level, up to Galaxy Level

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