Kamen Rider Dark Kiva vs Donatello (4Kids): who would win?

Kamen Rider Dark Kiva favored — Slight edge (~55%)

Kamen Rider Dark Kiva · Kamen Rider · King/Bat Fangire/Bat Fangire Reborn

Tier

5-A

Attack Potency

Large Planet Level

Speed

Sub-Relativistic

Durability

Large Planet Level

Donatello (4Kids) · Teenage Mutant Ninja Turtles · Dragon Form

Tier

5-A

Attack Potency

Large Planet Level

Speed

Supersonic, up to Massively Hypersonic+

Durability

Large Planet Level

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