The Rolling Pirates are from the New World, where only the strongest pirates can survive, so they must represent some great level of strength, though not enough to battle a Shichibukai directly, instead relying on research of Devil Fruit abilities to retaliate.
The crew, after escaping Moriah, used the second ship of the Rumbar Pirates that Brook gave them, due to him no longer needing it as he joined the Straw Hat Pirates. Though the ship has suffered damage from 50 years worth of time and battle, Franky repaired it and it was once again in perfect condition for the Rolling Pirates, and the rest of the Thriller Bark Association to sail out of the Florian Triangle.
Three years before current events, the Rolling Pirates were travelers in the Grand Line. Having traveled a bit in the New World, they sailed back across the Red Line via Fish-Man Island to the other side of the world. However, once on this side of the world, they got trapped within the Florian Triangle where they were easy prey to the ghost ship Thriller Bark. Seizing the members of the crew, captain Gekko Moriah stole their shadows, including the one of their captain Lola, and inserted them into various zombie creations on his island, particularly in the Wild Zombie animals that roamed the area. Shadowless and prone to the light of the sun, the Rolling Pirates were forced to live in fear in the forest of Thriller Bark to find a way to get back their shadows and defeat Moriah. At some point in time after having their shadows stolen and before the arrival of the Straw Hat Pirates they became members of Thriller Bark Victim's Association.
Eventually, the crew discovered a secret regarding Moriah and his Kage Kage no Mi: anyone can use the shadows stolen by him as long as they remain separate from their original container. Furthermore, they figured that multiple shadows can be inserted into one body, allowing for them to live in the light of the sun but risking them in gaining a multiple personality from the shadow's original owner. Working at night and hiding in the forests during the day with shadows not their own, the Rolling Pirates gathered as many shadows as they could, both by defeating zombies or stealing wild shadows that escaped the Thriller Bark crew. Their hope was the arrival of someone who would be able to use all their collected shadows in one amalgam form that would be able to stand up to Moriah and his potential ultimate creation: the massive zombie known as Oars.
Three years after starting their plan, the Rolling Pirates finally found someone strong enough to accomplish this: Monkey D. Luffy of the Straw Hat Pirates, who's shadow was the one stolen to activate Oars for Moriah. Using one-hundred shadows seized by them, the Rolling Pirates transformed Luffy into Nightmare Luffy, who easily defeated the giant zombie. Although this was successful, things turned for the worst as Moriah himself was not yet defeated and Thriller Bark finally sailed into the sun. Captain Lola realized that she had nothing to fear anymore from burning up and chose to stand in the sun risking her own life, nearly killing her until the final defeat of Moriah and the final reacquisition of the shadows.
After Moriah's defeat, the Rolling Pirates stood as allies alongside the Straw Hats during their brief encounter with ShichibukaiBartholomew Kuma. After Zoro sacrificed himself to stop Kuma's rampage, the Rolling Pirates parted ways with the Straw Hats, receiving Brook's old ship from Thriller Bark and fixed by Franky along with the rest of the Thriller Bark victims to part on as well as half of the enemy's treasure. Before leaving, they also gave Nami a Vivre Card for Lola's "mama", advising on how she may be able to help them in the New World.
The Rolling Pirates is the second canonical pirate crew (the first being Saruyama Alliance) to ally with the Straw Hats in the Grand Line. They are also the first canonical pirate crew to assist the Straw Hats in the fight against a main antagonist.