It could be the power to control others' emotions through singing. For example, the character could sing a sad song and make the enemies feel depressed and lose their will to fight.
Maybe the power to heal. The character with the singing bloodline might be able to sing special melodies that can accelerate the healing process of wounds, both physical and mental. This could be a very useful power in the dangerous world of Naruto. They could also use their singing to communicate with animals or summon them, similar to how some characters use their regular abilities to interact with the animal world in Naruto.
Well, it could be something like the ability to control elements in a completely new way. For example, instead of just the basic five elements in Naruto, the new bloodline might allow for the manipulation of light or dark energy. Maybe it gives the power to teleport short distances instantly, which would be a huge advantage in battles.
He could have the power of contagion. Naruto might be able to spread a weakened form of the virus to his opponents, which could slow them down or disrupt their chakra flow. Another possible power is enhanced adaptability. The virus in his bloodline could make his body adapt quickly to different situations or attacks, like developing immunity to certain jutsus.
He could have the power of flight. It's a common ability associated with angels, and it would give Naruto a huge advantage in battles and also in getting around quickly.
Well, having the Namikaze bloodline in fanfiction could endow Naruto with a natural talent for sealing jutsu. Minato was a master of sealing techniques. Naruto could inherit this and be able to create more complex and powerful seals. Additionally, it might give him a more refined sensory ability, allowing him to detect threats or chakra sources from a greater distance.
A plot could involve a villain using the singing contest as a cover to steal a powerful ninja artifact. While everyone is focused on the contest, the villain is sneaking around. Also, it could be that a character who has always been shy about their singing talent finally decides to enter the contest after some encouragement from friends. As they progress through the contest, they grow in confidence and become a better ninja as well. And there could be a sub - plot about a love triangle that develops between characters during the course of the contest.
He could have the power of instant regeneration. So, no matter how severe the injury, Naruto could heal himself in a split second. This would make him extremely difficult to defeat in combat.
Well, perhaps the bloodline could grant superhuman strength like Killer Croc has in the DC universe, which in the Naruto world might translate to being able to break through earth - style jutsu defenses more easily. Also, it could give the ability to swim at great speeds and hold one's breath for long periods, useful for underwater missions or battles near water sources in the Naruto world.
The powers could be related to the elements. For example, if Naruto had a Zanpakuto bloodline, his Zanpakuto might be able to control fire in a more refined way than his normal jutsu, like creating intense blue - white flames that can cut through anything.
One possible ability of the Ranton bloodline in fanfiction could be the creation of water - based illusions. These illusions would be more effective near water sources. Another ability might be the power to instantly freeze any liquid they come into contact with, which could be used both defensively and offensively.
In the fanfiction, Naruto could gain the power of enhanced perception. The Kyuubi's bloodline might give him the ability to sense things from a much greater distance, whether it's the presence of other ninja, hidden traps, or even changes in the environment. Additionally, he might have better control over his own emotions and be able to resist mind - control techniques more effectively. This is because the Kyuubi's bloodline could strengthen his mental fortitude, making it harder for enemies to manipulate his thoughts or feelings.