Vecna vs Ultimecia: who would win?

Vecna favored — Slight edge (~55%)

Vecna · Dungeons & Dragons · Greater God and boosted By The Serpent

Tier

2-A

Attack Potency

Multiverse Level+

Speed

Infinite

Durability

Multiverse Level+

Ultimecia · Final Fantasy · Dissidia

Tier

2-A

Attack Potency

Multiverse Level+

Speed

Massively Ftl+

Durability

Multiverse Level+

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