I recommend 'The Legend of Celestial Immortals'. The main character of the novel, Mo Xian, traveled to the Firmament World and became an outer disciple. He loved farming. While the various big shots were fighting over the Ginseng Fruit and Lingzhi, Mo Xian was using these precious spiritual medicines to feed sheep or rice. In the end, through their unintentional actions, all the important figures came over to beg Mo Xian to exchange for the spirit herbs. If you're interested in this novel, you're welcome to read it. I hope you'll like this fairy's recommendation.
Marshal Sengoku of One Piece ate the Rock Fruit. This fruit could turn him into a stone man who was immune to physical attacks and had a certain defense and weight.
Luffy's victory over Doflamingo in the manga was a combination of factors. His growth in strength, his unwavering will, and his ability to adapt to Doflamingo's tactics all played a role. Additionally, the support of his friends was crucial in tipping the scales in his favor.
A key element is the power clash. Doflamingo has his own set of powers from his original series, and when put against the RWBY characters' abilities, it creates intense and exciting battle scenes.
I really like 'Doflamingo's Unseen Side'. It presents a different perspective on Doflamingo. It has a lot of action scenes and also explores his relationships with other characters in the One Piece universe in a unique way.
One character that would make for an interesting pairing with Doflamingo in a crossover fanfiction is Zoro. Zoro's strong sense of justice and his skills as a swordsman would clash with Doflamingo's devious ways. They could have epic sword battles, and Zoro might be the one to cut through Doflamingo's strings, both literally and metaphorically. Also, Nami could be paired with Doflamingo. Nami's intelligence and ability to manipulate situations for her own gain, although in a more positive way compared to Doflamingo, could lead to some really interesting interactions. She could try to outwit him in a game of wits.