Here's a theory, Strawhat pirates reach the end on the Grandline, Raftel, they are ambushed by Commodore Smoker (perhaps promoted by then), with Tashigi, and these new guys Smoker plans to get his smoky mits on, and Hina too , then of course acompanied by Fullbody and Jango, all of these guys have got big and strong like the strawhats, and got various tricks up their sleeves.
Smoker vs. Luffy
Tashigi vs. Zoro
Hina vs. Nami/Robin (probably Robin, cos she can make hands, will Hina 'the black cage' can chain up most hana hana attempts from Robin)
Fullbody + Jango vs. Sanji and Usopp
and the rest of the crew will be assigned with new marines from Smoker's crew.
But wait! While this bloodbath is in progress, it is interupted by the Buggy Pirates! Buggy's gotten to be buff as hell (and increased bounty perhaps), and begins to rip up Smoker and Luffy, as his new super strong crew tear up the other fights, truly showing how the grand line can beef one up. Now it's pirates on pirates on marines, it's mental, the new fight line up would look like this
Smoker vs. Buggy vs. Luffy
Tashigi vs. Cabiji vs. Zoro
Hina vs. Robin
Alvida vs. Nami
Fullbody + Jango vs. Mohji + Richie vs. Sanji + Usopp
I can definatley see Franky vs a Marine beefcake, and also pitted agianst some circus strongman type.
Though now all groups are getting seriously blown, the strawhats, almsot become the common enemy, and begin to get beaten, but then in comes the real beef, Blackbeard pirates, with Mihawk alongside them, to test how strong Pirate Hunter Zoro has become since relentless shuffles in the new world. The Blackbeard pirates take advantage of the three groups being already beaten, and begin to clear a path to the grandline, smashing the other groups to smithereens, and Smoker, Buggy and Luffy find themselves fighting for eachother, to defeat Blackbeard (who has broken away from the WG, beat up Whitebeard himself, probably owned Buggy and the guys along the GL somewhere to properly start up a battle) Battle no.3 'The Battle for One Piece'…
Blackbeard vs. Luffy + Smoker + Buggy
Mihawk vs. Zoro (Zoro beat both Tashigi and Cabaji)
Lafitte + Van Auger vs. Sanji + Usopp + Fullbody + Jango
Doc Q + Stronger vs. Chopper + Richie (Mohji got pwned by Sanji or something)
Franky vs. Jesus Burgess
Smoker, Buggy, Fullbody, Jango, Richie fall to the blackbeard might. Then Doc Q and Stronger to Chopper, when he reveals his controlled Monster point, Usopp's Kabuto (or whatever weapon he's using then) gets shattered by Van Auger's shots, and then Van turns fire on Sanji, Usopp becomes a real man, and takes on van hand on hand, and beats him into shit (we;ve seen his stuff when he floored Butler Khaladore) zoro loses blood mr.1 style, but kills Mihawk, Sanji kicks lafitte into mere atoms, Franky stubs out Jesus Burgess like an old cigarette, while Blackbeard and Luffy's fight draws on, and on (remeber freeza and goku? yeah like that) but Luffy combats him with sometihng to do with light, and then nails him, he becomes the priate king, chopper cures the world (well mainly the victims of the past battle) Usopp becomes a brave warrior, Sanji finds that the All blue, was the water surrounding Raftel or Sharpshooter island (it will exist, all of his other lies did.....) Zoro kills Mihawk (maybe becomes disabled afterward), Nami mapped the world, Robin, found all the poneglyphs about the place, and Franky's ship was well good.....what an end to a fabulous story.