While I had originally wanted to run this as a chapter prediction, I'm not sure what exactly is going to follow the flashback we just had. So begins this fight prediction!
<We are taken to the Zoro vs. Pica battle, still at a stalemate. Zoro's nimbleness helps him keep Pica alert, but Pica's sheer brute power is tough for even him to counter>
Pica: You bastard! I've seen that the young master is now fighting your captain! And all because you got in my way of killing him!
Zoro: Me? You couldn't have stopped Luffy if he was alone, you bumbling oaf of a swordsman!
Pica: RAWWWR! YOU DON'T KNOW WHAT YOU'VE DONE! YOU'VE MADE ME FORSAKE MY DUTY TO THE YOUNG MASTER! NOW ALL I CAN DO TO REGAIN MY HONOR IS CUT YOU UNTIL THERE'S NOTHING LEFT!
<Pica covers himself in a stone casing. He and Zoro then leap at each other and clash swords. Zoro then goes on the offensive, slashing rapidly. Pica manages to counter his first few attacks, but Zoro manages to exploit an opening and slashes through Pica's armor>
Zoro: Are all New World swordsmen this weak? Gah, you're never gonna help me get stronger...
Pica: Huh...Hahahahaha! You think so, Roronoa Zoro?
<Suddenly, Pica's goes stiff, and Zoro sees with a shock that he has just stabbed pure stone>
Zoro: Huh? A rock clone?
<Suddenly, Pica's real body emerges from the ground behind Zoro. He slashes. Zoom out. We see blood spatter. Zoom back in. Zoro has a shallow cheek cut, but has managed to avoid the worst of the swing>
Zoro: I underestimated you...huh...
Pica: I failed once...I cannot hold back now!
<Pica sinks back into the ground, but quickly returns...this time with seven of him, all encased in stone>
Pica: Now, which one is really me, Roronoa Zoro?
<Zoro finds himself hard-pressed against the seven clones, who all have the same fighting ability. To make things worse, the seven Picas can change their form and swim through the ground. Zoro presses on, however, and manages to land a hit on one of the Pica's arms. It crumbles, revealing...Pica's real arm!>
Zoro: Haha! What luck! And on my first try too!
<Zoro focuses all of his attention on the "real" Pica, and batters him with a flurry of slashes. However, he does not notice Pica's other arm, holding Pica's real sword, appear from another Pica behind him...>
<Pica's sword arm slashes Zoro across the midsection. Zoro, bleeding profusely, struggles to get back up>
Zoro: What...how...how could you be in two different bodies?
Pica: Pehehehehe...You are naïve about my power, Roronoa Zoro! I am a stone assimilation human...meaning as long as my clones are connected to this stone, I can inhabit any of them! You thought I was inhabiting just one of the effigies...but in reality, I inhabit the very ground you stand on!
Zoro: He's more powerful than I thought! No mere man could face him...which is why a god must! KIKI KYUTORYU: ASURA!
<Zoro activates his Asura form, making Pica's giant body shudder and crack. Pica's seven smaller effigies tremble, but still stand, ready to fight>
Zoro: You're still gonna be a challenge...ahh, I like that!
<Elsewhere, God Usopp and all his disciples stand on the plateau, shocked at what Admiral Fujitora had said>
Riku: You're NOT going to stand in our way, Admiral?
Issho: I placed my bet on the World Government...and lost. I am no longer fit to stop evil. You have placed your bet on God Usopp to free you...now, the jackpot is yours.
<Suddenly, Kabu and Bian fly over to the plateau. They land on Viola's hand and tell her what is going on>
Kabu: We did it! The dwarf slaves are in full revolt, and Leo's gone to find Mansherry! Now we need you and the Straw Hats to come and destroy the SMILE Factory once and for all!
Viola: <looks around> I think you'll get a lot more than that! <To the mob> You decided to place your hope in the fight against Doflamingo, right? Well now, join in the fight! With you, we can destroy the SMILE Factory and bring down Doflamingo!
<The mob roars in consent. The war party has now been mobilized>
Viola: We're on our way. Now guys, I need you to look for the other Straw Hats, as well as anyone who is allied with us. We need as many people as possible!
Riku, to Issho: So Admiral, will you join us?
Issho: No...I cannot interfere in this. However...there is one thing I must do now...
<Back to the Zoro vs. Pica fight. Zoro, now in Asura form, is fending off the seven Pica effigies while doing severe damage to the landscape>
Pica: Your demonic presence does not intimidate me, Roronoa Zoro! For it is nothing compared to the real hell I have experienced!
Zoro: This is it!
<The seven Picas leap at Zoro, and a blast of smoke and metal ensues. When the dust clears away, Zoro is standing tall, next to seven crumbling Pica effigies, which are struggling to remain on their legs>
Zoro: You gave me a good fight...but the stone you're hiding under will crumble after I show you this new move!
Pica: You still...KNOW NOTHING, RORONOA ZORO!
<The real Pica, no longer hiding in the stone effigies, rises out of the ground in front of Zoro. Quickly, Zoro tries to counter, but it is not enough. He is blasted off the giant Pica effigy, and lands hard on the ground. The two swords in his hands were blasted away by the strike, leaving only Wado Ichimongi in his mouth. Right then, Pica re-inhabits his giant stone effigy and repairs it until it was in its original condition>
Pica: So, Zoro of the Santoryu style...how can you use your "new move" on me with only one sword?
Zoro: Hehehe...what you've done is perfect! Because...my new move only needs one sword!
Zoro: ARISE...KIKI ITTORYU: INDRA!
<Zoro's Asura aura begins to expand until it reaches its new form: A giant behemoth god, as tall and as wide as Pica>
Zoro: FALL, LIGHTNING GOD!
<Wado Ichimongi, covered in a huge aura, slashes across Pica's entire body. It then starts to crumble, and Pica's real body, slashed from head to toe, falls with it>
Pica: Why? Why couldn't I protect the young master? After all I did, I failed...!
<Flash 25 years in the past. In the South Blue, a carnival is taking place, and one of the exhibitions is the freak house. Pica, abandoned at age 5, has spent the past ten years under the care of the manager. In return, he lifts weights and then gives his famous "speech">
Announcer: That's Pica the Big Baby, folks! He just lifted 500 pounds. And now...chant with me! SPEECH! SPEECH! SPEECH!
Pica: Well...hello everyone...I...
<The crowd erupts into enormous laughter. Sure, the weight-lifting part looked cool, but hearing such a muscled male talk like that was the most hilarious thing they had seen in a long time. Pica, however, is turned off by their laughter. Why did they always do this to him? Why couldn't-Suddenly, a whip hits Pica in the back, making the crowd laugh even more>
Showrunner: What are you doing, kid? You better talk, or else!
<The showrunner brings the whip down on him again, causing Pica to cry out in pain. The crowd is roaring with laughter that is louder than ever before. Pica gets up, when something in his brain snaps. All the frustration of 10 years of the crowd's mockery rushed into every part of his body. Pica knew only anger. Knew only rage. Knew only to kill the people who paid to mock his voice>
1 Hour Later
Marine: Can you tell us what happened here?
Escaped Spectator: It was just horrible...that kid...I can't even look now!
Marine: Let's see the damage-
<The Marines look around the circus tent in amazement. Everything was covered in blood. In the stands lay the bodies of the spectators who didn't make it out in time, and the Marines see additional bodies on the ground: the circus managers who had enslaved Pica for so long. Pica had taken out so much rage on them that their bodies were barely recognizable>
Marine: This is outrageous! We must find the murderer at all costs!
<In the shadowy depths of the carnival, Pica hides. He starts to weep. He hated to kill people or even hurt them. Why did they have to mock his voice like that? Why couldn't he have been one of them? He spends the next few days on the run, until one day he is approached by someone>
Doflamingo: Ah, are you this person I heard about?
Pica, frightened: Are you with the Marines? Are you gonna take me away?
Doflamingo: Of course not, my dear boy! I've just heard the news of your recent actions...and I think you would be a perfect fit to join my crew!
<Some minutes later, Pica stands in front of Doflamingo, Vergo, and his (rather small) group of followers>
Doflamingo: So, what do you say? Join us?
Crew Member: HAHA! HIS VOICE! DO YOU REALLY EXPECT-
<Quickly and efficiently, Doflamingo cuts through his former crew member, killing him>
Doflamingo: We judge our crew on ability, not external things. Anyone who makes fun of you, makes fun of us.
Pica: You have done me...such a great favor! I will do all I can...to repay that!
<Flash forward to the present>
Pica: I've done a grave sin...but please forgive me, Young Master. And help me...to be as loyal to you as Roronoa Zoro is to his captain!
<Pica finally lands on a large bed of stone. Zoro stands nearby, along with Bian>
Zoro: One's down...now off to the SMILE Factory!
Bian: Hey, I specifically told you it was that way. Do you have any sense of direction?