Okay, I got a lot of ideas here, and a whole lot of text, and I’m not even sure if any of these powers have been taken or not, but please bear with me on this.
Anpu Anpu no Mi (Amp Amp Fruit)
Power: Paramecia type fruit. The consumer becomes an “Amp man”, and is able to distort the force exerted by him or around him, making the force stronger or weaker as he chooses. The user can amplify foreign objects only when they are within his vision, but will always be able to amplify the functions of his body or objects he is holding regardless of sight. If the user has a hold on an enemy, he is able to amplify or de-amplify the insides of their body (an example would be de-amplifying the force of a heartbeat to slow or stop the flow of blood, which admittedly is very cheap). The user can also distort sound, but only that which he creates due to the issue with sight. Finally, to what extent the user is able to amplify or de-amplify depends on their own willpower (Ex: Spandam = meh, Luffy = pain, Whitebeard = Apocalypse). It should be noted that almost all devil fruits have a set limit to their power, and it is the users themselves who grow in strength and cunning. The Anpu Anpu fruit is an exception, as it is one of the only fruits that’s powers grow stronger with the devil fruit user.
Weaknesses: Amplification is a double-edged sword: some of the distorted force is prone to turn back and damage whatever is amplified. For instance, amplifying the power of a rifle, while magnifying the strength and speed of the shot, can likely tear the gun apart. However, it is possible for the user’s body to grow used to these effects, thereby taking reduced damage, but that factor applies with their body alone, and the damage can still accumulate. Also, loss of sight renders the user unable to apply his powers to objects non-adjacent to his body. If it overpowers the user’s own will, haki will completely neutralize any sort of amplification. Finally, amplification only applies to physical force and sound: the user cannot distort the effects of temperature, light, poison, etc.
Jiten Jiten no Mi (Spin Spin Fruit)
Power: Paramecia type fruit. The consumer becomes a “Spin man”, and is able to rotate his body parts at a high velocity, much like a drill or a fan. The user is very limber and flexible, since nearly every joint is able to spin and bend in various different directions.
Weakness: No long ranged capabilities.
Fun Idea: Sanji is able to go into Diable Jamble by spinning on one leg. So if this guy can spin however many parts of his body, all at the same time . . .
Inu Inu no Mi: Model Hyena (Dog Dog Fruit: Model Hyena)
Power: Zoan type fruit. The consumer gains the ability to transform into a hyena and a “Hyena man” with vastly improved senses and agility, as well as inhuman savagery.
Weakness: May become prone to uncontrollable fits of laughter.
Nezu Nezu no Mi: Model Usagi (Rat Rat Fruit: Model Rabbit)
Power: Zoan type fruit. The consumer gains the ability to transform into a rabbit and a “Rabbit man” with vastly improved senses and agility. Though a seemingly tame ability, the speed granted by this fruit can prove to be deceptively powerful when paired with a consumer possessing superhuman strength. Also, in the user’s admittedly ridiculous animal and half-animal forms, they normally have an advantage due to the enemies’ inability to take them seriously.
Osen Osen no Mi (Pollution Fruit)
Power: The consumer gains the ability to putrefy the world around him, becoming a “Corruption man”. The user’s touch can cause plants to wither and flesh to rot, and the air he exhales becomes toxic.
Weakness: Due to the nature of the devil’s fruit, the corruption can be washed away with water.
Kyojin Kyojin no Mi (Giant Giant Fruit)
Power: Zoan type fruit. In a similar fashion to Chopper’s Human Human fruit, the consumer becomes a “Human Giant”, with the ability to transform into a giant or a half-giant. This could also be consumed by animals, objects, or other giants, making for a plethora of bazaar or even monstrous combinations.
Denka Denka no Mi (Charge Charge fruit)
Power: Paramecia type fruit. The consumer becomes a “Charge man” who is capable of channeling a sort of electrical charge to any part of the body, increasing its functions to superhuman levels. For instance, charging his arm would greatly increase its strength, speed, and durability, charging his ears would grant him incredible hearing, etc. The user can also create a “discharge” in the form of a bolt of electricity, giving him a ranged attack. Since the body increases its durability when charged, it does not suffer the painful backlash that the Anpu Anpu fruit user is subject to. It is a close cousin to the Anpu Anpu fruit, in that it’s true potential is not limited to the user’s strength or intellect, but by their will.
Weaknesses: Unlike its cousin, the powers of the Denka Denka fruit cannot be applied to anything other than the body. If a body part is wet, the charge will be dampened and lose some of its power, delivering a painful shock to the user in the process.
Again, if anyone has already thought of any of these, then I apologize for my ignorance and surrender the ideas to you. Except for the Amp Amp fruit. That one’s mine, no way around it.