In this fanfiction, Naruto would gain the ability to manipulate the elements in new ways. Each tailed beast is associated with a different element or combination of elements. By having all of them, he could create complex elemental attacks that are not possible before. For instance, he could combine the fire of one tailed beast with the water of another to create steam - based attacks. His healing factor might also be enhanced as some tailed beasts possess regenerative abilities. This would make him even more difficult to defeat in combat.
In such fanfiction, Naruto may gain the ability to heal himself more quickly. Since the tailed beasts possess a great amount of life - force energy, Naruto could tap into that to accelerate his own healing process. His mental abilities could also be enhanced. He would be able to withstand greater mental pressure and use the tailed beasts' collective wisdom to make better decisions in battles. Moreover, he could potentially create a chakra shield that is extremely strong, using the combined chakra of all the tailed beasts to protect himself and his allies.
The abilities would be numerous. Naruto could gain the power of enhanced perception from one of the tailed beasts, being able to sense enemies from much greater distances. Another tailed beast might give him the ability to manipulate earth, allowing him to create earthquakes or form defensive earth structures. And with the combined power of three tailed beasts, he could potentially break through any type of chakra - based defense. His stamina would also be greatly increased, enabling him to fight for longer periods without getting tired.
He would likely gain enhanced cutting and slashing abilities. Each of the seven swords has its own unique properties, so Naruto could use them in combination with his existing ninjutsu. For example, he could use the swords to channel his chakra more effectively, increasing the power of his attacks.
In this fanfiction, Naruto could control all the tailed beasts because of his unique chakra nature. His chakra is very special and has a high compatibility with the tailed beasts' chakra. Also, his experiences with Kurama might have given him insights on how to handle other tailed beasts. He probably communicates with them on a spiritual level and convinces them to work together with him.
Well, in many fanfictions, Naruto might use his strong will and the power of his Uzumaki heritage. His natural chakra reserves are huge, which helps. He also has a deep understanding of friendship and the tailed beasts' pain from his own experiences. So, he can connect with them on an emotional level and gradually gain their trust, thus being able to control them.
Well, in such a fanfiction, the reader having all the tailed beasts could lead to a really complex plot. First, they would have to deal with the internal struggle of controlling such immense power. Maybe they start as an outcast in the ninja world because people fear their power. But as time goes on, they learn to use the tailed beasts' powers for good. They could form alliances with different villages, using the power of the tailed beasts as a deterrent against common enemies. And they might also discover secrets about the origin of the tailed beasts that no one else knew, which could change the whole perception of the ninja world.
One interesting storyline could be about the tailed beasts forming an alliance outside of the control of humans. They might work together to protect their own kind and the world in a different way than the shinobi. For example, they could create their own hidden land where all chakra - based creatures are welcome.
In such a fanfiction, Naruto would likely be extremely powerful. With all the tailed beasts' chakra at his disposal, he could easily overpower most foes. He might be able to perform new and incredible jutsu that were previously unimaginable. For example, he could combine the unique abilities of each tailed beast to create a super - attack.
He could develop the ability to transform into a more powerful form that combines the features of all nine tailed beasts. Maybe he could have nine tails of different colors or shapes, each representing a different tailed beast, and with each tail comes a special power.
Naruto might gain superhuman strength like Kratos. He could easily break through solid rock or lift extremely heavy objects. His speed could also increase, allowing him to move so fast that enemies can barely see him. Maybe he could also have the ability to summon the blades of chaos, which he could use in combat in a unique way, like combining them with his kunai.