I recommend One Piece: The Great God Usopp to you. This book is a story about Usopp. It tells the story of how he obtained the League of Legends system through an accidental transmigration and became invincible. If you want to read a One Piece Doujinshi novel with a deceptive cloth as the main character, this book is perfect for you. I hope you will like my recommendation.
Friendship turned to more is a very common theme. Since they start as crewmates with a normal friendship in the original, fanfictions often explore how that can develop into a romantic or deeper emotional bond.
One great Zoro x Usopp fanfiction is 'The Unlikely Bond'. It beautifully explores their friendship evolving into something more. The author does a wonderful job of depicting Zoro's tough exterior softening towards Usopp, and Usopp finding new courage in Zoro's presence.
Well, it could be that there's a plot device like an ancient artifact. This artifact might have the power to draw out and combine the Akatsuki powers. The Akatsuki members themselves might be tricked into contributing their powers to this artifact, and then the protagonist or an antagonist gets hold of it and gains all those combined powers. It's a common trope in fanfiction to use such magical or mysterious items to bring about extraordinary power combinations.
I recommend "Super Class Monitor System" to you. The main character of this urban life novel is Liu Junlin. He is the world's most famous scientist, entrepreneur, entertainment superstar, sports superstar, and writer. He is also their class monitor. I hope you like this fairy's recommendation. Muah ~😗
There are often super powers related to magical creatures in Harry Potter super powers fanfic. For instance, a character might have the ability to transform into a Phoenix at will, which would give them the power of rebirth and the ability to fly extremely fast. Another super power could be the gift of seeing the future with absolute clarity, not just in glimpses like Trelawney's prophecies but seeing entire timelines. And there could be a super power where a wizard can communicate with all magical plants and use them as allies, for example, making the Whomping Willow stop attacking or getting the Mandrakes to help in a fight.