Law has plenty of options. He could teleport himself behind marines which are observing the fight, cut them in pieces, and attach their heads onto his body. This way Fujitora would not be able to attack him, and he would have to stop DD from attacking him.
Law kills Cesar, and then he gets surrounded by Marines and Doflamingo. Law pulls out his sword and slices a dozen marine fodder, and while no ones watching he swaps hands of some marine he sliced with his own hands (readers don't actually get to see him doing this).
Fujitora takes out his sword and says: "Law don't be foolish and surrender."
On to which Law respond: Ok, I surrender myself into the hands of the authorities of the world government.
DoFlamingo screams in anger: "The hell you do, you're mine little traitor" and charges at him.
Doflamingo's attack gets blocked by Fujitora and he sends DD flying.
Fujitora says to his subordinates: "Put handcuffs on him and take away his weapon" which is what they do, while Law puts no resistance.
In the background we see sliced marines trying to put back their bodies, and saying: "has anyone seen my hands, whose leg is this, I don't think these are mine kintama"
Then DoFlamingo returns, pissed off at everyone, and Law starts provoking him verbally even more. DoFlamingo starts arguing with Fujitora about giving him Law, while Law is pushing his buttons with verbal provocations, while marines in the background are still trying to assemble their bodies: "a: Has anyone seen my hands b:Are these your hands? a: lol no! I don't have tattoos."
Eventually this arguments between DD and Fujitora escalated into a fight, so we get to see a lot of destruction, Green bit sliced in half, large portion of island destroyed etc, after the fight ends Law drops off his fake hands with kairoseki handcuffs, teleports his real hands back, teleports his sword into a hand, charges at Fujitora and cuts him in half.
Then he cuts everything else also.
I have an idea about who will fight who in this arc.
First Law will make Doflamingo and Fujitora fight each other, as it is explained above.
Then after a long exhausting fight, a blood will be dripping from both of them, and their breath will be heavy.
Then Doflamingo will say " Fine, have that little prick, I don't need him, I don't need this fight" and then he'll leave.
At this point Law drops off his fake hands with kairoseki handcuffs, teleports his real hands back, teleports his sword into a hand, charges at Fujitora from behind and cuts him in half, then cuts him in pieces.
After that Law teleports away.
Little bit later, Fujitora just managed to put himself back, when Zoro arrives on the island with that little dwarf.
Fujitora is pissed so he attacks Zoro. Here we have a fight between Zoro, Ussop, Robin and dwarfs vs hurt Fujitora and marines.
Zoro wins
Back on Dressrosa Violet has decided to go with Sanji, and as she's running towards him saying "I love you Sanji take me with you" Doflamingo arrives and cuts her head off, in front of Sanji. So Sanji vs Doflamingo fight starts.
Sanji wins
And Luffy beats Don Chao, Diamante, Jesus, Cavendish and everyone else on the tournament.
I will be fun to see how far away from the true story I will be.