I think that the circumstances of the war has been rigged to favor the Scadrian victory proponents. This is a world vs world war scenario!
Nobody has mentioned the fact that the Stormfather would also participate in this war. He's not a Shard, so the Shard participation restrictions would not apply to him. I would like to see how the Scadrian army will fare when a Highstorm is summoned in their midst. Or the Koloss army. Or even the Lord Ruler for that matter!
Oh! Does anyone remember that the Nightwatcher (not a Shard!) would probably grant Rosharans Boons that will help them win the war? Just imagine strategy and tactics unit with 100 'Super Taravangians'.
Some Rosharan creatures like the Ryshadium and Santhids have been shown to have some form of intelligence. Is it too much of a stretch to assume that other creatures like the Chasmfiends would have enough intelligence to fight for the Rosharan side if their world is threatened?
I would also like to see how Koloss, Mistings or even Mistborns and Inquisitors would fare against a platoon of Thunderclasts.
There are also Stormform Parshendi (and 'Otherform' Parshmen following the Everstorm's arrival). I will say nothing about the Heralds, Voidbinders, Unmade or other types of Voidbringers since we don't know yet what they are capable of.
By a native Rosharan