Ultimate Devil Fruit Theory
Okay, so, with the current fight between Imu and the forces of Elbaf, I have come up with a theory. I think that the three Major types of Devil Fruit (Paramecia, Zoan and Logia) all have an Ultimate fruit to which the others relate/are derived from. I'm not good at laying out these things, so forgive me if the formatting is terrible, but here goes.
Akuma no Mi/Devil's Fruit
I think, despite appearances that this is in fact the ultimate Paramecia fruit. I think Imu's physical traits might just be how he always looks and that the powers derived from this fruit is essentialy "Whatever another Paramecia can do". For example -
* Buildings and trees take on a life of their own similar to Big Mom's Homies
* Can take possession of people like Kelly Funk's Jacket Jacket fruit.
* Can grow in size like Sanjuan Wolf's Deka Deka/Huge Huge fruit.
* Creates cannons and things like Baby 5's Buki Buki/Arms Arms fruit.
* Powering up others with Omen and shifting his own body somewhat similar to Gecko Moria's Shadow Shadow Fruit.
Basically, aside from the flame halo which might be just a similar visual metaphor to the Zoan Hagoromo, there's no trait Imu has displayed that indicates it is one of the other two types.
Gomu Gomu no Mi/Gum Gum Fruit/Hito Hito no Mi Model: Nika/Human Human Fruit Model: Nika
Couldn't make that title easy on us. Anyway, I think the Nika fruit is the ultimate Zoan fruit for various reasons, but a few that stand out most to me are as follows -
* It's the only Zoan fruit that apparently doesn't turn off. Luffy is always a rubber man, he doesn't have human, half-Nika and Full-Nika forms, he always seems to be Half-Nika at least.
* It is the only Awakened Zoan with a cloud hagoromo instead of the flame one.
* It is the only Zoan we've seen where the apparently full animal form doesn't even appear until it is awakened.
* Whenever an artificial Zoan fruit fails, the victim is left in a state of constant smiling and laughing.
Part of this could be put down to Oda simply not intending this from the start, leading to the obvious differences in implimentation between the Gum Gum fruit and the standard operations of a Zoan fruit, but now that that's happened, we may as well try to explain why it is the way it is.
Yami Yami no Mi/Dark Dark Fruit
And lo, the ultimate Logia. Obviously, even from its introduction we were shown that this fruit was unique amongst Logia and I'll lay those out the same way I did the others. -
* It is described as "The most evil" of Devil Fruit powers.
* By touching other DF users, it can nullify their abilities
* Unlike other Logia it doesn't actually make its user intangible to harm.
* While the Devil's Fruit seems to impart the powers of other Paramecia type fruits, the Dark Dark fruit is the only one we've seen that seems capable of active theft, with Blackbeard somehow taking the power of Edward Newgate's Gura Gura/Quake Quake Fruit directly from his body, and sustaining both at once, something thought to generally be impossible, if statements from Jabra are to be believed.
* It is also the only Logia that is based on an abstract concept as opposed to some sort of matter or energy.
I don't really have much more to say on this one in particular cause it's probably actually the best explained of the three thus far, with its basic mechanisms being known unlike the Devil's Fruit and not being a massive deception like Luffy's.
Conclusion
Now then, what does the existence of these three fruits mean, and is there any real point in defining them as 'Ultimate'? I dunno. Maybe I'm wrong, maybe I'm right. Maybe there's a Supreme Ultimate Devil Fruit with the powers of all three out there? Or the actual Sea Devil from whom these powers are supposedly derived? I'm not sure and at the minute I don't have enough information to form a solid theory, mostly I just wanted to share my thoughts with you all, and who knows. Perhaps one of you has been paying closer attention and just having the info here has helped you come up with your own take way hotter than this one.