@zero:
I would have agreed with you if Zoro is a real life person in our world. However, OP doesn't always follow the rules of our world. Otherwise Pell should have died from the bomb and Usopp shouldn't have survived after being hit by a 4-ton bat. I'm sure the rules would be bent, otherwise Usopp probably lost to Van Auger in a battle.
I agree. Even the idea of Sanji or Franky defeating a shichibukai seemed ridiculous to me. Zoro probably only stands a chance with Mihawk.
Your first paragraph is classic OP. Oda gives exceptional abilities to his named characters, but luckily only to the extent that they don't die :)
I also agree with the 1st half of your second paragraph. I don't expect Sanji or Franky to defeat any Shichibukai. However, I do expect Zoro to defeat any and all of them. Correct me if i'm wrong, but Mihawk is the 1st shichibukai introduced. Following Shounen tradition, he will most probably be the strongest shichibukai. Therefore, if Zoro is capable of defeating him, it implies he's now capable of defeating the other shichibukai.
@UsoppKing:
See…here's the thing: The 7 Gods of the Sea are a world power. not the people themselves, but their status. You saw Crocodile, and if they're all on par with him or greater is yet to be seen. And the first person to mention bounty needs to remember that bounty is seen as a person's threat to the World Government, not their strength.
A member of the Shichibukai doesn't gain their power in the world from their physical strength, but the strength of the intimidation they can instill in other pirates. The job of one of the Shichibukai is to keep small pirates in Check and, if need be, join together with the World Government against the Yonkou.
I don't see the stronger Strawhats fighting evenly with the Shichibukai as fanservice, I see it as them fighting on the level of the Crew of the Pirate King. Look at Shanks, a former cabin boy for Gol D. Roger, and now he's one of the most powerful people in the world. That speaks volumes about how strong the crew for the Pirate King needs to be.
Here's what I see for the Strawhats at the end:
Luffy - Pirate King
Zoro - World's Best Swordsman
Robin - Learned the True History
Nami - A map of the world
Chopper - A great Doctor
Usopp - A Brave Warrior of the Sea (Sniper King, anyone?)
Sanji - Finding All Blue (Also, finally finding a woman lol)
Franky - Built a Ship that Sailed to the End of the Grand Line
That's quite a tall order, and who says that none of them will be able to fight on par with shichibukai except Luffy and Zoro by the time this all comes to pass?
/endrant+
On the contrary, we first learn of bounties as strength. It's not until we are told by Aokiji that bounties are not only a measure of strength, but also a measure of threat to the WG. And so far, aside from Robin (chibi robin) and going out on a limb with Foxy, everyone's bounty so far seems to be a measure of strength.
The intimidation factor comes from being able to do something that requires strength. Let's take BB for example. It's obvious he has never confronted the WG / Marines, however, he has the potential of getting into the Shichibukai by doing what? Taking down a 100M or higher wanted pirate.
Pertaining to Roger's crew, we can't know for sure that everyone was on Shanks' level. Shanks is obviously an exception, we have Shanks and Buggy who were apprentices together. One went on to become a Yonkou, and the other became some pirate in East Blue not worth the Marines' time. This is not a Buggy critism btw, so please be cordial.
As for other SHs fighting Shichibukai, I just don't see it. Zoro has been training from the time he was a kid, his goal is to become the #1 swordsman, this is a big hint at where his future is going. No one else in the crew has a goal of this proportion (i'm not counting Luffy).