Flapper is a dwarf from Tontatta Kingdom who first appeared on Green Bit, when he stopped Leo from taking Robin's clothes and belongings. He participated in Operation SOP and became a temporary victim of Sugar's Hobi Hobi no Mi.
Flapper, like all the other dwarves, is small and has a large fluffy tail and a pointy nose. He has a light red polka dotted cap, a red sweater, gray pants and yellow boots. 
When transformed into a toy, he became a small black bear, like all of the other dwarves who were transformed after attempting to attack Sugar. He was given a hat with vertical stripes, as well as a sword and shield.
Flapper appears to be just as gullible as the other dwarves as he believed Usopp's lie about being a legendary hero.
Abilities and Powers
It can be assumed that Flapper possesses the same abilities as the rest of his people such as great strength, agility, and the ability to cultivate any plant. He is also capable of using a lance, sword, and shield.
After Usopp and Nico Robin were captured and taken to Tontatta Kingdom, Flapper was convinced that Usopp is the legendary hero who came to help the dwarves. He later stopped Leo from taking Robin's clothes, because she is a friend of Usopp.
While Usopp and Robin have a feast, Flapper commented on how he was moved to tears when Usopp claimed to be the descendant of Mont Blanc Noland before the other dwarves requested Usopp to lead them in the battle against the Donquixote Family.
The dwarves, Usopp, and Robin later traveled to the underground base in the Flower Field and rendezvous with Thunder Soldier in preparation for a decisive operation to overthrow Donquixote Doflamingo. They planned to attack the underground world and their top priority was defeating Sugar, the Devil Fruit user who transforms humans into toys. When they finally commenced Operation SOP, they infiltrated the underground world through a secret tunnel and arrived at the trade port.
After Thunder Soldier separated from them to go to the royal palace, the dwarves prepared to go to the central tower where Sugar was located. When Usopp was spotted by two of Doflamingo's men, the dwarves stripped them and knocked them out. Flapper was amazed at how Usopp "pretended" to be scared in order to lure in the enemy. After Usopp and Robin put on disguises, the dwarves continued on to the central tower.
After they entered the tower, Robin and Bian lured Trebol away so that Leo's group could knock out Sugar with the Tatababasco grape. The dwarves charged into the room and rushed at Sugar. Their attack failed and some of the dwarves, including Flapper, were transformed into little black bears. Sugar then put them under her control and ordered them to kill everyone in the tower. Flapper's and Leo's groups lunged at each other with their weapons raised. They were interrupted when a ship thrown by Trebol crashed into the tower.
When Sugar forced the Tatababasco into Usopp's mouth after he was subdued by Trebol, Usopp made a horrible expression that terrified Sugar to the point of losing consciousness. With Sugar's power undone and the primary objective of Operation SOP completed, the toys returned to their original forms and the dwarves wept over Usopp's success.
Flapper and the other dwarves then carried Usopp away from an enraged Trebol while Robin held him back. They were surprised when Hajrudin picked up Usopp. When the former slaves declared their allegiance to their savior, Usopp ordered his newfound followers to destroy the SMILE Factory and the dwarves shouted out Usopp's name.
Doflamingo later trapped Dressrosa in his "Birdcage" and forced everyone imprisoned into a survival game. During the chaos, Flapper's group was reunited with Wicca and Kyros' dwarf group when Kin'emon arrived at the underground trade port. Doflamingo also placed a price on the heads of twelve people. The dwarves were surprised when Doflamingo not only included Usopp in his hit list but also placed the highest price on his head. With Usopp's new followers turning into enemies, the dwarves, Usopp, Robin, Rebecca, Sabo, Koala, Hack, and Bartolomeo fled to the surface.
After running through the stands of Corrida Colosseum, they reached the top of the old King's Plateau. The dwarves were then reunited with Riku Doldo III and Viola. While Leo and Kabu volunteered to go with Rebecca to find Monkey D. Luffy, the rest of the dwarves decided to go to the SMILE Factory to assist Franky.
Once they arrived at the factory, the dwarves used Pink Hornets to display a message to the dwarves inside the factory, informing them of Doflamingo's trickery. After the dwarves inside revolted and unlocked the doors, Franky and Flapper's group entered.
While Franky battled Senor Pink, the dwarves at the factory were contacted by Viola and they were worried when they heard that Mansherry was being forced to use her healing powers on the defeated Donquixote Pirates' officers. They were then overjoyed when Leo and Kabu successfully rescued Mansherry.
They continued watching Franky's battle as he and Senor Pink took each other's blows. They cheered when Franky emerged victorious. With Senor Pink defeated, the dwarves proceed with the destruction of the SMILE Factory.
After exiting the destroyed factory, Flapper and the other dwarves carried Franky outside and looked in unison towards the city, much to Franky's confusion. Flapper told Franky that his heart felt lighter, but the cyborg responded by telling them to stop staring and run away from the shrinking Birdcage instead.
While fleeing, they ran into Roronoa Zoro, Kin'emon, and Kanjuro. When Zoro informed them of his plan to stop the Birdcage, the dwarves were awestruck. Since the factory could not be cut by the Birdcage, the dwarves and Franky used it to push the Birdcage back.
When Luffy finally defeated Doflamingo and brought the Birdcage down, the dwarves rejoiced with tears of joy as Luffy's victory was announced to Dressrosa. During the aftermath, the dwarves gathered in front of Kyros and saluted their commander.
Four Emperors Saga
The Stories of the Self-Proclaimed Straw Hat Grand Fleet
Sometime after the Straw Hats left Dressrosa, Flapper became part of Leo's newly-formed pirate group, the Tontatta Pirates. The crew then went to assist the Dressrosa citizens in rebuilding their homes. After they received a new ship from the citizens, the crew immediately checked it out.
"Gang" Bege's Oh My Family