Suggested by Sonic Gokudera is a very earnest fighter who is always trying to improve his abilities. You can’t help but have a lot of respect for the guy. Usopp is not quite as skilled in combat. His equipment is pretty good for sure, but the guy doesn’t have the physical abilities needed to give Gokudera a true fight. He would quickly be overwhelmed and Gokudera will be able to blast away at him with his fire cannon. Gokudera wins.
Luffy can beat Usopp pretty easily. Usopp once tried to usurp leadership and it didn’t end well for him. Luffy is too strong and has Gear 2. That form works the same way as Super Saiyan. It multiplies his power. Luffy wins.
Zoro has sword skills that he can use to slash through the strongest defenses. No one can stop him. Usopp can try but in the end he’s not in Zoro’s league. Zoro is quite possibly the strongest Pirate in the Great Seas. Zoro wins.