Let’s assume that it’s the whole planet vs the other. Fused and Radiants vs. Malwish and Basinites. The Scadrians have a larger technological advantage, with medallions, airships, the beginning of self-propelled missiles. They also have a magical advantage with mistings, ferrings, twinborn, and after TLM, mistborn again.
“But radiants are stronger”. Not necessarily true. 3rd ideal and lower don’t have shardplate, so are weak to emotionally Allomancy. And even full radiant could be trapped in a pulser’s bubble. Also, scadrial has the means to mass produce aluminum, which can be used to stop shardblades. Frankly, I can really see the rosharans winning. They work on a very static style of war, where as scadrians (northerners at least) have over 1,000 years of record military experience that changes. Rosharans are stuck in rank formations using spears.