The Stranger vs Rad: who would win?

The Stranger favored — Slight edge (~55%)

The Stranger · Marvel · Base

Tier
1-A
Attack Potency
Outerverse Level
Speed
Massively Ftl+
Durability
Outerverse Level

Rad · Dungeons & Dragons · Old One

Tier
1-A
Attack Potency
Outerverse Level
Speed
Ftl, up to Immeasurable
Durability
Outerverse Level

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