Everyone on the ship was shocked by the declaration the boy with the straw hat made. Take down Alvida? Her crew members considered it impossible.
Alvida herself felt especially provoked by the declaration. Her grip tightened on the mace, and she growled. "I'll teach you some manners you little punk!" She lifted up her mace and moved toward the boy.
In the original, Luffy had beat Alvida with a single rubber punch. Luffy knew he could do the same with Haki, but he decided to toy with her before defeating her, just dodging her attacks. Alvida finally brought her mace down. Luffy used his basic Observation Haki to dodge the strike.
Alvida shouted in frustration and rushed towards Luffy. She slammed her mace down and he narrowly dodged the attack. The deck cracked due to sheer force. Alvida groaned and smashed the mace down on Luffy. He moved his shoulder and head slightly and she missed the strike. This happened a few more times and Alvida's moves became more sluggish and more predictable.
At that point the deck was splintered at many places and many of her crewmates were knocked off the ship due to the force of the mace strikes. Koby was hiding in corner, shivering in fear. Alvida herself was blinded as with rage. She didn't care if her crew was hurt or not, she just wanted to damage her opponents even a little bit.
Luffy, however, was enjoying every second of it. The way he effortlessly dodged each attack showed how much he had developed as he trained as a kid. Luffy was enjoying himself so much that he let his guard down once and Alvida struck him with her mace. He didn't have enough time to coat his torso in haki and received the full force of the attack. He flew across the deck, smashing into a crowd of pirates.
Alvida smiled maniacally, thinking she had finished him for good, her eyes widened with surprise as Luffy stepped out of the dust cloud, cracking his knuckles as he smiled with scratches on his body.
"You think that hurt, you fat pig? My grandfather could destroy your ship with a punch and he trained me. I could punch you with the force of a bazooka." With those words he rushed forward at a speed that stunned Alvida.
He coated his fist in Armament Haki and used his momentum, adding to the force of the punch. His fist connected with Alvida's stomach and her body rippled. One second Alvida was on the ship, and the next she was flying into the horizon.
"Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah!!"
Her scream was highly audible, striking fear in her crew's hearts. Luffy turned towards her crew, and they scrambled into boats, rowing for their lives. Only one boy remained on the ship with Luffy.
"Koby," Luffy called, "come out." Koby came out of his hiding place and stared at Luffy intently. Luffy asked, "Do you know the way to Shell Town?" Koby nodded frantically. He then set down a rowing boat fastened to the ship and they both jumped in. Koby grabbed an oar and began rowing. After a few minutes into the ride, Luffy broke the silence.
"You said you wanted to join the Marines, Koby. Why so? I'm not asking so because of criticism, but I want to know: what is your dream?"
Koby was surprised by the question. No one had ever asked him if he had any dreams, much less what they were. He started to reply. "Well… I hope to join the Marines and become an admiral, but I don't think it's possib— OUCH!!"
Luffy had knocked him on the head, creating a large bump there. "I didn't do that because I disregard your dream, but because you lack belief in it. My dream is to be the king of the world, and I have believe in my dream so I know I can do it. If I die, I die. You need to believe in yourself if you want your dream to come true." Luffy said.
Koby rubbed his head and said, "Belief…". Then his head snapped back to Luffy and said, " WAIT, YOU WANT TO RULE THE WORLD?!" Luffy muttered that that was not the point.
"Besides, I wouldn't mock you because if I want to rule the world, I'll need some challenges along the way." Luffy said. Koby found determination in his words and swore in his heart to fulfill his dream or die trying. But one question lingered.
"Mr Luffy, why are we going to Shell Town?" Luffy heard him and smiled mischievously.
"I'm going there to recruit someone, you might know him," he said, leaving suspense in the air.
It was time to recruit the famous bounty hunter Zoro.
Author's note: I'm going to be making many of these actions my own scenes as I can't really recall some of the things that happened in the anime and am to lazy to go check it out. But I'll keep most of it canon, but with no df's in the story. If you have any questions please ask. Also please send some stones my way. Thanks.