ARC trooper armor was plastoid, which is bulletproof and heat/blast resistant. ARC trooper wins easily. Nick Spencer vs a Mack truck.
The knight. They're trained for battle their whole lives. Full-power Dovahkiin (level 252/all perks) vs Smaug.
The tiny horses. Square-cube law, and all that. The hollow bones of a duck would snap under that much weight. The Courier vs the Lone Wanderer.
It depends on what they're hauling, and where they hit. Also depends on what kind of dump truck. I mean, a dump truck can be anything from a three ton modified pickup to a 360 ton Liebherr mining truck. Ford vs Chevy.
Ford, the Chevy would break on impact, or just fall apart beforehand (looking at you corvette) Honda vs Hyundai
If its just a sword, then Aku, if it's the sword, then the foolish sakurai warrior Stormtrooper Deathtrooper vs Clone ARC Trooper