Buy the official One Piece Card Game PRB-01 The Best Japanese booster box display, a premium special selection set featuring top cards, popular characters and standout designs from earlier One Piece releases
While there are guidelines to keep in mind when deck building (no Game Changers in Exhibition or Core, no mass land denial through Upgraded, etc.), the bracket system is emphatically not just "put your deck into a calculator, get assigned a rank, and be ready to play." I deeply appreciate the tools that websites like Moxfield and Archidekt have put together to give you an overall estimate, and they've done some fantastic iteration to help emphasize intent as wellbut I want to stress that any estimate is just an estimate

Ascendant Evincar Avenger en-Dal Belbe's Portal Blinding Angel Complex Automaton Death Pit Offering Divining Witch Eye of Yawgmoth Flowstone Overseer Flowstone Slide Kill Switch Kor Haven Laccolith Titan Lin Sivvi, Defiant Hero Mana Cache Moggcatcher Murderous Betrayal Oracle's Attendants Overlaid Terrain Pack Hunt Pale Moon Parallax Inhibitor Parallax Nexus Parallax Tide Parallax Wave Predator, Flagship Rath's Edge Rathi Assassin Rhox Rising Waters Rootwater Thief Saproling Burst Saproling Cluster Seahunter Shrieking Mogg Sivvi's Valor Skyshroud Behemoth Skyshroud Poacher Sliptide Serpent Spiritual Asylum Stronghold Gambit Tangle Wire Volrath the Fallen ther Barrier
Of the red backgrounds, I like Guild Artisan and Street Urchin the most