The Player (Magikarp Jump) vs Tatsu: who would win?

The Player (Magikarp Jump) favored — Slight edge (~55%)

The Player (Magikarp Jump) · Pokémon · Protagonist

Tier
9-B
Attack Potency
Wall Level+
Speed
Peak Human, up to Relativistic+
Durability
Island Level

Tatsu · Sakamoto Days · Base

Tier
9-B
Attack Potency
Wall Level+
Speed
Supersonic+
Durability
Wall Level+

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