@grunk:
Chopper can turn into a giant demonic monster and Nami can shoot hurricanes and thunderstorms (Thundercanes. I'm predicting it.)
Usopp's "strength" lies in being a sneaky underhanded bastard. Now while that's not classical strength it accentuates the raw strength of the other members because he does things they can't.
He's the wildcard.
Did you forget usopp was the genius who created the weapon, that got her that powerful in the first place, who then wound up on a sky island to learn more…? it was thanks to him she is interested in the weather and those powers, you think kuma sending her there was a coincidence?
at most nami and usopp are tied, she had a rod he created that could call weather and cause thunder storms how effective would it be on top brass or VA or Admiral class fighters? None, when usopp gets stronger, it is only natural that he will be stronger than her physically , but in terms of power hers is not different than his, they are both died imo. She can get random enemies thunder bolted and usopp can fire fast and take out people, as much or more people.
one more thing...
Isn't it true they include the ship as apart of the crew? if so they have already hit 10, I saw two more crew members at most maybe even 3 more and temp crew members/people he and the crew are helping out.
Money D. Luffy, Roronoa Zoro, Nami, Usopp, Sanji, Tony chopper, Nefertari Vivi (do not kill me, she is a member of the crew oda "cares about her"), Nico Robin, Franky, and Brook.
What ever straw hat comes after this is speculation.