Chesu Chesu no Mi

The Chesu Chesu no Mi is a Paramecia-Type Devil Fruit that allows the user to take on the abilities of various Chess pieces. “Chesu” is the literal word for Chess in Japanese. The user can switch between each form near-instantly.

Abilities
Pawn Form - The user becomes very small and agile, but at the same time very frail and weak. Thus, the most effective way to use this form is for spying or sabotage.

Bishop Form - The user’s arms and legs become very long, enabling fighting from afar, incredible climbing skills, and the ability to run on all fours very quickly. However, it’s essentially like painting a target on your back.

Rook Form - The user’s skin becomes extremely tough and durable, but their movement speed is greatly reduced. They additionally gain inhuman strength.

Knight Form - This form is a balance of the three aforementioned forms. The agility of the Pawn, the long limbs of the Bishop, and the armor of the Rook. The downside to this form is that it is very strenuous to do, and may kill the user if overused.

King/Queen Form - The user retains their normal body, but gains the ability to influence people’s decisions and actions through a psychological link. The victim of this ability can fight back though, and can do the same to the user if they are mentally strong.

The general idea is for the ability to be much like the game of Chess itself; there are many ways to win, but also many ways to lose.