I know it's a bit long, but I wanted to do it in one part rather than make it a series. Enjoy.
Lieutenant: Vice Admiral Bastille, sir! This just came from headquarters.
Bastille: So, the investigation has finally ended. I have to admit, I was looking forward to this day with both excitement and dread. The only question now is how shall we write this dark conclusion?
Lieutenant: About that, sir. Rova from Cipher Pol 8 has just arrived and he has some news you might like to hear.
Bastille: Is that so?
Rova: Yes. It turns out that the Straw Hats may very well do our job for us, we just have to take care of the formalities and cleanup.
Bastille: What do you mean?
Rova: To put it metaphorically, the pirates take out the heart after we take out the veins and a few arteries. CP4, CP8, and CP9 have already made significant strides to this end.
Bastille: I understand. So what do we have to do?
Rova: If my analysis is correct, the Straw Hats will be approaching you with an offer for a temporary ceasefire. I implore you to take it. As fighting on two fronts is just not beneficial to the mission.
Bastille: Understood. Communications, get in touch with Vice Admiral Smoker of G-5 immediately! We're going to need another set of hands on this one, and he's just the guy to have. He's dealt with these pirates in a similar situation.
In the palace
Doflamingo: Oh my, Straw Hat and friend. How nice of you to come together. I hear the royal family is a matching set once again, minus a certain mother. That can only mean you've taken out Juguete. And my tiny neighbors are here too! Did you come to borrow a cup of sugar?
Luffy: Franky, Sanji, and other gramps are already working on your big three. Nami, Brook, Rebecca, and the rest of those guys are working on the rest of your high-ups, while Robin and Usopp, and Kin'emon are keeping your footsoldiers at bay, and Brook is the one who took out your toy maker. Chopper and the other samurai are watching the ship as well as keeping an eye on Tora-guy.
Zoro: The others went to see how Robin, Kin'emon, and Usopp are doing, so I figured I could lend a hand here, not sure where here is, but yeah. I brought these guys too.
Rebecca: Stay back and stay frosty. I don't know why it took three of us to bring you here
Dold III: Doflamingo's powers make it so numbers are both advantageous and a detriment. We must attack simultaneously. Viola, use your senrigan to track his movements and keep us posted on the other bouts.
Luffy: Actually, you guys can go back to the other fighting. We're good here.
Gancho: Now listen, Luffyland. We need to be careful with-
Luffy: Gomu Gomu no Gigant Rifle!
Gancho: Oh to fuck with it! Tontas, diverging helix formation! Go!
Luffy's punch is flanked by dwarves on flying bugs. Doflamingo easily dodges Luffy's attack, but takes minor damage from the dwarves.
Doflamingo: So that's how it is.
They all continue sparring for a while. Jumping ahead a bit....
Robin: We of the Straw Hat Pirates request asylum under the sanction of Pirata Immunis Judicia.
Maynard: I know what Rova said, but there is no way we can-
Bastille: We accept your terms.
Robin: This agreement will not be considered fully honored until we bring you Donquixote Doflamingo himself.
Smoker: Understood. Until we have Donquixote Doflamingo in custody, your bounties will all be frozen but you will remain on the island.
Robin: Very good.
Marines and pirates start walking toward each other.
Bastille: Well then. You guys seem to have a plan. Mind sharing it with the rest of us and telling us what we can do?
Nami: I suppose you could start by telling us what you've been doing on your end.
Maynard: We've basically been doing the administrative equivalent of what you guys are doing.
Sanji: What do you mean?
Smoker: We've been looking into Doflamingo's main ties to the world above and the world below.
Bastille: Using various channels, we've been contacting them and feeding them a little of their own medicine.
Robin: You mean you took a page from Doflamingo's book?
Smoker: Exactly. We ran another news story saying Doflamingo's activities have been uncovered and his bounty reinstated. They've been buying it like narcotics at a black market fire sale.
Sanji: The Marines can run fake stories too?
Bastille (grinning): Well, it's not fake so much as it is...premature, let's say.
Luffy calls out for Sanji in the distance.
Sanji: Well, duty calls. I knew he'd need help fighting Doflamingo. That guy's wicked powerful.
Robin: Anyway, we're going to need you guys to put on a little bit of a show. Where are the people you've captured?
Maynard: In the prison bays. Why?
Nami: Bring them out here. Let's just say we're going to give Doflamingo some eye vomit.
Maynard: Don't you mean eye candy?
Nami: You heard me.
Robin: And while they're doing that, Nami, I have a job for you.
Luffy: He's distracted. Remember the plan, Zoro!
Luffy: Gomu Gomu no Gigant Bullet!
The attack connects, partially blindsiding Doflamingo, who was being swarmed by the dwarves.
Doflamingo (getting up): So that's how it is. Send the midgets in and while I'm dealing with them you attack me. I see there's a hole in your plan. Allow me to fix that. Overheat!
He shoots a whip at several nearby trees, taking out many dwarves in the wake of the blast and debris.
Doflamingo: Just take away the midgets and problem solved!
Gancho (voice somewhat faint): Don't worry about us. We're okay. Just focus on the fight.
Luffy: You bastard!
Doflamingo: Now, I think it's time for me to take control of this fight. Parasite!
Luffy: Damn it. I can't move. Zoro, NOW!
Two invisible forces seem to collide between Luffy and Doflamingo for a moment.
Luffy: Gomu Gomu no Jet Pistol!
Doflamingo: Nice try. But I can react faster than you think. Parasite!
Luffy: Damn it, where's SANJI! when you need him?
The fight continues like this for a few more rounds, with Doflamingo's grasp being broken and Luffy charging only to be stopped again.
Doflamingo: This is getting old fast.
Sanji: Côtelette Deux!
Doflamingo looks down just in time to see Sanji plant two feet firmly between his kidneys and rib cage.
Doflamingo: Black Leg! So nice of you to join us.
Sanji: So what do you need me to do?
Luffy (whispering): Kick him in the face when I try to punch him.
Zoro: Trust me, you'll get it.
Doflamingo: Let's play freeze tag!
Luffy: Gomu Gomu-
Sanji: Collier Epice!
Sanji kicks Doflamingo in the face, just as predicted. Doflamingo, realizing their strategy, tries to fall back as they continue the three man combo, changing who attacks based on who Doflamingo grabs.
Luffy: Darn. We're going to have to find a new way to beat the shit out of him now.
Luffy: Cuz if we do it more he'll go over the cliff behind him.
Zoro: Hm, good point. We're actually pretty high up. Hey, you can see the port from here.
Sanji: So you can. I can even see the girls from here! HI NAMI-SWAAAAN! HELLO ROBIN-CHWAAAAN!
Luffy: Hey look, Doffy, I can see some of your guys there too! There's the lanky creep, the oozy creep, and the bulky creep.
He looks toward the port and sure enough he sees Trébol, Pica, and Diamante lined and tied up on the dock
Doflamingo: What the fuck is going on!? I'm a shichibukai with connections reserved only for the Celestial Dragons! Why the hell are my people getting arrested? Just my luck, a couple low hanging clouds. Pardon me a moment, gentlemen. Sora no Michi!
He ties on to the first cloud and starts moving toward the next.
Nami: Mirage Release! Gust Tempo!
The clouds in front of Doflamingo vanish and the one he is attached to dissipates.
Luffy: Hold on guys!
Doflamingo: Huh? AAAAAAAAHHHH!!!
Everyone within earshot winces as Doflamingo crashes through the wooded canopy, landing with all kinds of unpleasant noises.
Luffy (landing after slingshotting himself, Zoro, and Sanji off the cliff): Did we do good?
Nami: You did great. Now get ready, we're about to have one very angry, very unpredictable megalomaniac coming our way.
Doflamingo: Fujitora! Bastille! Maynard! Smoker? What the hell are you doing!? Those people work under me! Therefore they are granted immunity under my status as a Shichibukai. Release them immediately!
Luffy: Doffy, so good of you to join us. Shishishishishishi.
Bastille: Um, about that. I'd like to, but we've received intelligence that says all these guys were part of some kind of rebel faction that overthrew the kingdom of Dressrosa ten years ago.
Doflamingo: They were serving under me at the time and that mess occurred after I became a Shichibukai. They're immune from the law!
Bastille: Smoker, you explain it. You know this stuff better than I do
Smoker (with a slight hint of a smug grin): With pleasure, Basty. You see, under the Reveric charter, article 8, section 1, clause D, any country aligned with the World Government in the midst of a coup shall thereby be treated as a non-member of the World Government until such a time that internal order is fully restored. As such, during the event ten years ago, Dressrosa was not part of the World Government, therefore you were acting outside the safe jurisdiction in which your status applies.
Doflamingo: What? Do you honestly expect me to believe that crock of shit?
Fujitora: Of course not. So we thought that it would be a good idea to start making arrests now in order to better get our point across.
Doflamingo: Oh, I see what you're doing. Haha. Nice try. Just because this means that the Donquixote Pirates are no more doesn't mean this is the end of Joker. Oh far from it! Just like the joker card can go anywhere in the deck, I can go anywhere in the underworld! I have options.
Doflamingo: Is something funny, Devil Child? Well? Out with it all of you! What's the little joke you're having?
Smoker: You want this one, Basty?
Bastille: Nah. How about you take it, Maynard.
Maynard: You see, we've been doing a bit of homework and have found out several of your key underworld connections. As is the case with your crew, proper measures are being taken.
Doflamingo: Yeah right! Now I know you're fucking with me! My main connections are so discreet even I can't know their true identities! So there's no way you could possibly-
Bastille: "Fallen Angel" Augustus Dirge, Garza "Symphonic Gun" Badel, and "Silver Blood" Ramud Falza.
Doflamingo: How could you possibly....
Maynard: Actually, these were just hunches. We weren't certain until your reaction clinched it just now.
Doflamingo: Huh? What the fuck is going on!? This can't be happening! This isn't happening!
Smoker: As you can clearly see, we have all the makings of a game of 52 pickup right here. All we're missing is the joker.
Doflamingo: No. No fucking way! You can't take me down! Don't you know who I am? I'm the first offspring of Saint Delamancha and Saint Aldanza of the Donquixote Family! I'm international royalty, an angel who came down from the holy land!
Fujitora: Now I know you're desperate. You told me at the beach on Green Bit that you threw your title away.
Doflamingo: Yeah, I rejected it, but it never goes away. It's like a curse you're born with. How else could I call CP-0? Even if I knew the number, they wouldn't have come if I weren't a world noble.
Maynard: You really are using everything in your arsenal. Do you have the Official Decree, Rova? I'd like you to meet Rova of CP8.
Doflamingo: What decree?
Rova: This was hand-delivered to me by Fleet Admiral Sakazuki earlier today after the whole newspaper fiasco. It's from the office of the 3rd Sacred Elder.
Doflamingo: The 3rd!
Rova: It officially strips you of any privileges granted through your birthright. We didn't get it fast enough to fix the papers, unfortunately...
Bastille: But it's enough to keep you from running back to daddy. So, how does it feel, knowing your own father notarized and authorized your dis-ownership? You can see where he signed it twice. Once to place the request, and again to authorize it. I'm sure you know the signature all too well.
Doflamingo (staring at the paper): Fa...Father...That...kniving...heartless, self-entitled bastard!
Fujitora: And that about wraps it up, unless you want to pick through every nitty-gritty bit of evidence.
Doflamingo: I'm not going down like this! If I'm going down, I'm taking everything here with me!
He raises his hands and then thrusts them forward. As he does so, the tops of two buildings fly toward the group.
The buildings turn harmlessly to rubble. Doflamingo starts to run toward the palace, knocking things over on his way in an attempt to slow down his adversaries as the pirates and Marines chase after him.
Bastille: Smoker, he's going after the royal family!
Robin: We can cut him off. You just keep the family safe!
Smoker (already going Logia): Got it! You just be sure to catch up!
Nami: Robin, Usopp! You're the only ones who can fight at this range! It's up to you!
Usopp: Hissatsu Midori Boshi: Piranha Pit!
Doflamingo finds himself surrounded by drooling carnivorous plants, but easily dispels them with his wires.
Robin: Dos Fleurs, Peekaboo!
A hand covers each of his eyes, halting him as he tries to get them off. These sort of things continue until the pursuers are almost at the palace. Doflamingo throws open the door.
Doflamingo(with the grin of a man who's snapped): At least I can take the damned Riku family with me!
A pair of metal legs kick Doflamingo in the chest. The kick is enough to knock him off the steps and into the front courtyard.
Doflamingo: What the hell was that?
Rebecca: Doflamingo!? We weren't expecting you. Good thing Vice Admiral Smoker came and told us you were coming, otherwise we wouldn't have been able to welcome you properly.
Smoker and the rest of the Riku family join Rebecca outside, standing over Doflamingo as the pirates and Marines arrive. They now all stand in a circle around a different man than they remember.
Doflamingo (now crying): No! It can't end like this! It won't! Ove-
He has time to get to his knees and throw his hands in the air, trying to do two Overheat attacks.
Luffy and Bastille simultaneously kick Doflamingo, both hitting one of his shoulders. They then each grab one of his arms and pin him to the ground. To anyone watching Doflamingo from the front, it would look like a man on his knees raising his hands to the heavens before falling down.
Doflamingo (in tearful hysterics): NOOO! WAAAHAAHAHAHAHAHA! It can't end this way.
Bastille (trying to keep himself composed): It has, and it will.
Smoker (looking on in disbelief, speaking somewhat distantly, yet sternly): Sergeant, read him the decree.
Sergeant: Shichibukai Donquixote Doflamingo, acting upon the wishes of the Marines and World Government and with the powers granted to me, you are hereby-
Doflamingo: Shut up! Don't say it!
Bastille: Be quiet!
Sergeant: You are hereby found to be in abuse of your installed title. We therefore strip you of the rank and title of Shichibukai and surrender all rights that come with it.
Bastille produces a pair of seastone handcuffs and places them on Doflamingo, who moments before had stopped shaking uncontrollably and now has a small ring of white foam around his mouth.
Sergeant: Sir, he's in total shock. He's not responding at all. He's completely inchoherent.
Smoker: Just drag him then. That about wraps things up here. Straw Hats, we'll discuss the specifics about closing our deal back at the port.
Maynard: Actually, why don't we all take some time to cool off here?
Smoker: And why should we do that, Maynard?
Maynard (pointing): That's why.
Smoker looks around to see Tashigi and several soldiers clearly shaken up by what they had just seen. Off to one side, Nami, in the same state, is already being comforted by Robin and Sanji.
Smoker: I suppose you're right. Listen up troops, anyone who needs a moment to... catch their breath, can take their time getting back to the ships.
Bastille: Very well. Maynard. You're on towing duty (pointing to Doflamingo).
Smoker, Maynard, Bastille, and some of the soldiers start walking away, dragging Doflamingo. After a little while, Usopp and Zoro leave too and the courtyard falls stiflingly silent.
Dold: ...I have found it is rather unpleasant to sit around moping outside. It is best done inside, on a couch, in front of a roaring fire with blankets and hot drinks. What do you say?
Everyone looks up at the king and nods meekly but with a sincere smile. The soldiers enter first, led by Tashigi, the men who helped her to her feet walking on either side of her. Shortly thereafter, Sanji and Robin bring Nami in. And lastly, Luffy, perhaps the deepest in thought of the group, joins the rest inside.