@electricmastro:
Doesn't feel right to call Zoro and the others secondary/supporting/minor characters just because they aren't Luffy. I mean, I'm not saying they have to be exactly like Luffy, but they're not decidedly less focused on characters like Paulie or Hatchi either. I see Luffy as the leading main character while calling Zoro and the others as main characters in their own right..
For Nami, Zoro and Usopp, and Sanji, I'd consider them closer to Main Supporting characters since we have much more POV focus on them than most of the rest of the crew. But in general, they act more like support characters outside of their own major arcs. They are all there to support Luffy overall, and neither of these characters really carry the story without Luffy.
I would go as far as saying that even though every Strawhat has a dream to follow and a story to tell, as Strawhats they put supporting Luffy's dream of becoming King of the Pirates above their own dreams. That's what defines them as a supporting character in the story, and this definition is mot a means to say they are background or throwaway characters, but to illustrate that a Main character is typically the most important character in the story. A Main Supporting character (Deuteragonists) comes directly after the Main character, like a sidekick or rival or love interest. Not all the Strawhats are equal in this type of importance. Zoro or Nami could be considered deuteragonists, while Robin is more of a supporting character like Chopper, Brook and Franky who all directly support him, practically no questions asked