Demogorgon vs Ultima: who would win?

Demogorgon favored — Favored (~65%)

Demogorgon · Dungeons & Dragons · In the Abyss

Tier

2-C

Attack Potency

Low Multiverse Level

Speed

Infinite

Durability

Multi-Continent Level, up to Low Multiverse Level

Ultima · Final Fantasy · Incomplete Manifestation

Tier

LOW 2-C, up to 2-A

Attack Potency

Universe Level+, up to Multiverse Level+

Speed

Massively Ftl+

Durability

Universe Level+, up to Multiverse Level+

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