Kamen Rider Build vs Arceus: who would win?

Kamen Rider Build favored — Slight edge (~55%)

Kamen Rider Build · Kamen Rider · The Real World

Tier

HIGH 1-A

Attack Potency

High Outerverse Level

Speed

Average Human, up to Immeasurable

Durability

High Outerverse Level

Arceus · Pokémon · True Form (The Heart/Original Spirit)

Tier

1-A

Attack Potency

Outerverse Level

Speed

Omnipresent

Durability

Outerverse Level

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