Several characters have been shown to either possess unique abilities and/or have been been confirmed to have a Devil Fruit power, but without it being directly named.
Here’s the list of the strongest unnamed Devil Fruits:
#15 – MORLEY
Morley’s unnamed Devil Fruit that allows him to move and shape the ground he touches like clay.
#14 – KIN’EMON
Kin’emon’s unnamed Devil Fruit which transforms small items placed on a person’s head into something that can be used as a disguise (based on the user’s imagination and memory) which lasts until removed. Kin’emon refers to it as sorcery.
#13 – KANJURO
Kanjuro’s unnamed Devil Fruit that allows him to bring whatever he draws to life. Like Kin’emon, he refers to it as sorcery.
#12 – CHARLOTTE OPERA
Charlotte Opera’s unnamed Devil Fruit that allows him to generate and manipulate large quantities of whipped cream.
#11 – CHARLOTTE GALETTE
Charlotte Galette’s unnamed Devil Fruit that allows her to control a fluid substance, which she can use to bind people’s hands to prevent them from moving.
#10 – JEWELRY BONNEY
Jewelry Bonney’s unnamed Devil Fruit, which allows her to manipulate the age of any person, including herself.
#9 – SCRATCHMEN APOO
Scratchmen Apoo’s unnamed Devil Fruit which allows him to morph body parts into instruments and use music as a weapon.
#8 – BASIL HAWKINS
Basil Hawkins’ unnamed Devil Fruit, which allows him to create straw voodoo dolls and use them to redirect physical damage from his own body. Damage incurred by the dolls will be exhibited by those whom the doll represents. Hawkins can also transform into a straw-man. Kizaru stated that it is not a Logia.
#7 – EUSTASS KID
Eustass Kid’s unnamed Devil Fruit, which allows him to manipulate magnetic forces.
#6 – UROUGE
Urouge’s unnamed Devil Fruit, which allows him to convert damage taken into strength, expanding muscles.
#5 – JOZU
Jozu’s unnamed Devil Fruit, which allows him to turn his body into diamond.
#4 – X DRAKE
X Drake’s unnamed Devil Fruit, an Ancient Zoan which allows him to take the form of a dinosaur.
#3 – VINSMOKE REIJU
Vinsmoke Reiju’s unnamed Devil Fruit. Reiju was confirmed to have eaten a Devil Fruit in the One Piece Magazine Vol.1, and while she had been shown to have some unique abilities, it is unknown which of those are Devil Fruit powered and which are scientific enhancements.
#2 – FUJITORA
Fujitora’s unnamed Devil Fruit that gives him the ability to manipulate gravity.
#1 – MARCO THE PHOENIX
Marco’s unnamed Devil Fruit. While this fruit’s power is classified as a Zoan, due to the uniqueness of the phoenix itself, the additional powers it grants may be considered similar to those of Paramecia (the somewhat “superhuman” power that affects the user’s body: regeneration) and Logia (the generation of blue phoenix flames).