Kamen Rider Slash vs Boarbatusk: who would win?

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

Kamen Rider Slash · Kamen Rider · Megid War (1-15)

Tier

9-B, up to 6-C

Attack Potency

Wall Level, up to Island Level

Speed

Massively Hypersonic, up to Massively Hypersonic+

Durability

Wall Level, up to Island Level

Boarbatusk · RWBY · Base

Tier

9-B

Attack Potency

Wall Level

Speed

Hypersonic

Durability

Wall Level, up to Large Building Level

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