Since we have not been properly introduced to haki all new world pirates and vice admiral/admirals were nerfed during the whitebeard war. Oda could not show them go all out without revealing things that were for later like the black hardening, which he might not even have thought of at that point of time and more.
No one was nerfed there. The black hardening is likely nothing new, but just a graphic detail to explictly show whether Haki is used or not. At least that's how I see it. In fact it makes no sense for the New World Pirates not to go all out if they wanted a chance of rescuing Ace. The Marines on the other hand didn't need to go all out because all they had to do was to stop them from reaching the scaffold.
Yonkou is not a powerlevel. It is a title you get when you are one of the four most influential Pirates in the New World. Marco took over the Whitebeard Pirates, and since they are like a big family, all their allies likely as well. He also became the ruler of Whitebeard's territories, but failed to keep them all.
I definitely think Marco is stronger than Doffy. Easily.
I disagree with you then. Doflamingo has clearly shown he doesn't really fear admirals or shichibukais, actually, the only person he seems to fear is kaidou, and that's probably because kaidou seems to have a huge army against which Doflamingo has no answer by himself or his crew.
He's not immortal. He will die if you drop him in the sea.
Well then if what you're saying is true, then by that logic then luffy is screwed right now?
At the moment of the manga Luffy didn't show that he could pose a threat to Doffly alone.... It's the first time that an opponent of Luffy is surpassing him in pure combat skill (aside Ace ^^)
You just need enough endurance and to hit him often enough. Oda said in an SBS that Marco can't heal indefinitely and that there are limits to his powers.
Right! I mean think how much energy he spends to heal - we don't see him tired but he's a top tier fighter living for quite some time in the New World. And if we take the bounties in account, I can only guess he had one above or level with Ace, so at least 550kk. You don't give a bounty so high to weaklings. Add the most rare of DF and being a freaking PHOENIX! I mean anyone can be killed but he'd be one tough cookie.
He was already part of WB's crew when he clashed with GolD Roger. Which means he is a Veteran of the New World. Who knows he might even have been told by Whitebeard about the One Piece and will help Luffy guide to it, Shanks is of course the most obvious possibility and Buggy^^
Oh, yeah. Forgot about that he's so old. He aged well :P