Imu is one of the most important characters in the world of One Piece. Introduced rather recently to the fans during the Reverie arc, it was revealed that Imu is actually the sovereign of the entire world and that they sit on the Empty Throne, which signifies the highest power in the world. It is believed that Imu existed long ago during the time of the Void Century and that they were possibly a part of the 20 Monarchs who stood against the Ancient Kingdom.
Somehow, they found their way to the top and became the sovereign of the world. Under them are the powerful Gorosei and, given that Imu is the highest of the pecking order, they are also going to be one of the very strongest in the story. Recently, it was confirmed in One Piece that Imu does indeed have a Devil Fruit power, however, what exactly this power entails isn't made clear just yet. Nonetheless, just the silhouette is enough to speculate and there are some abilities that fit Imu more than others.
5 Mythical Zoan Dragon
A Mythical Zoan dragon is one of the likeliest powers that Imu could possess. In One Piece 1085, when Sabo attacked Imu with Hiken, they quickly transformed and opened their jaws wide enough to eat the fire. Not many creatures are known to be capable of eating fire and fans know that dragons, especially western dragons, are capable of doing this.
While Kaido was an eastern dragon, Imu could have a Devil Fruit resembling a western dragon. This would also tie into the meaning of the name Celestial Dragons and the Hoof of the Dragon, which is their symbol. At the same time, Vegapunk was known to be experimenting on western dragons on Punk Hazard and that could certainly tie into this as well.
4 Mythical Zoan Hito Hito no Mi
Another strong possibility for a Devil Fruit power for Imu could be the Hito Hito no Mi, but a mythical demon version of it. This could be a direct contrast to Luffy, who also has a similar Devil Fruit. While Luffy is Nika and the embodiment of laughter and freedom, Imu could be its opposite. Imu could be a person or an entity that brings only destruction and reduces things into nothingness.
What exactly this Devil Fruit could be can't be predicted as it would likely hold the name of a God within the One Piece world, just like Nika. As fans know, Nika is not something that exists outside of One Piece, so it is highly likely that it would be a similar case for Imu as well. Nonetheless, a Mythical God with the power of nothingness and the capability of utter destruction would be perfect for Imu.
3 Mythical Zoan Sea Devil
It is also possible that Imu could possess a mythical Zoan Devil power. This is very different from them being God with capabilities of destruction. Instead, Imu could actually be the Devil itself. The Devil has been brought up in One Piece on countless occasions and it is believed that the Devil Fruits themselves originate from the Sea Devil.
If this Sea Devil is actually real, then it is possible that Imu could actually possess the powers of this creature. This would also explain why they were able to eat Sabo's fire as that would stem from a Devil Fruit and most likely not work against the progenitor of such a power. Imu could very well have the highest level of power when it comes to Devil Fruits and, thus, be able to devour anything related to a Devil Fruit ability. This also ties into the fact that Imu is often seen being in touch with nature in the Room of Flowers within Pangea Castle, which shows that they are one with nature.
2 Chaos Devil Fruit
Another interesting ability that Imu could have up their sleeve is the power of chaos. In One Piece 1085, Imu was seen referring to themselves with the pronoun "Mu," which is a childish way to talk and indicates that Imu might as well be a child who is immortal, but at the same time it also translates into "Infinity" or "nothingness." It could also closely translate into "Void," which would mean that Imu could have the powers of the void itself.
In One Piece 1085, Imu managed to transform into a giant creature with sharp teeth capable of swallowing fire. This could mean that Emu might be able to transform into a mythical creature with the power of Chaos. In Greek mythology, Chaos is a state that existed before the creation of the universe. Before the new world, as fans know it now, was created, Imu could have used the powers of chaos to cause the Void Century. Essentially, this power would make Imu the God of the Void.
1 Ancient Weapon Uranus
The Ancient Weapon Uranus is among the weapons of mass destruction that are known to be capable of destroying the entire world. While Pluton and Poseidon have already been introduced to the fans at this point, Uranus remains to be unintroduced. It is very likely that the power of Uranus belongs to none other than Imu themselves. Imu could wipe out the Kingdom of Lulusia from the sky and the people of the nation noted that something was flying above them.
This flying weapon could very well be Uranus and fans know that the one who controlled this weapon was none other than Imu. It is highly likely at this point that Imu has the power of Uranus at their side and that they intend to cleanse the world once again, just as they did in the past during the Void Century. Whatever powers Imu might possess will eventually be revealed to the fans, however, theorizing about them is always fun for One Piece fans.