Iuno vs Mirage Mewtwo: who would win?

Mirage Mewtwo favored — Slight edge (~55%)

Iuno · Wuthering Waves · Arrow

Tier
5-A
Attack Potency
Large Planet Level
Speed
Sub-Relativistic+
Durability
City Level

Mirage Mewtwo · Pokémon · Base

Tier
5-B
Attack Potency
Planet Level+
Speed
Massively Ftl+
Durability
Planet Level+

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