It could have super speed, allowing it to quickly dash across the battlefield and catch enemies off - guard.
It could have the ability to see chakra flow in extreme detail. This would allow Naruto to detect hidden traps or enemies who are using chakra - concealment techniques. He could also use it to analyze the weaknesses in an opponent's jutsu just by looking at the chakra patterns.
She could have the ability to manipulate space - time like Kaguya. Maybe she can create portals or slow down time in a different way. It would be a natural extension of Kaguya's powers.
The tiger could be very protective. Since Laxus is its owner, it would be fiercely loyal and would not hesitate to defend him against any threat. It might be a bit wild at heart still, with a playful side that comes out when it's just with Laxus in a safe environment.
He might still have his enhanced physical abilities. Even as a pet, Naruto could be super strong and fast. This would be useful for Ruby in a lot of ways. For instance, if they were in a dangerous situation, Naruto could use his speed to escape or his strength to protect Ruby.
He could have the ability to manipulate the concept of law itself. For instance, he could make it a 'law' that any attack aimed at him misses. This would be like a natural defense mechanism. Another ability could be to set laws on the use of chakra, like 'only I can use fire - style jutsu in this area' which would disrupt his opponents' combat strategies.
Naruto could have a Zanpakuto with the ability to create illusions of hope. Given his character, it would make sense for his Zanpakuto to have an ability that gives his opponents a vision of a better future if they stop fighting. This would be a non - violent way of ending battles, which aligns with Naruto's ideology. Another possible ability could be to transform his chakra into a tangible form that can be used to either heal or boost the strength of his allies. It would be like his chakra is being channeled through the Zanpakuto in a more controlled and versatile way.
With the Rinnegan, he could have abilities like the Six Paths techniques. He might be able to use the Preta Path to absorb chakra attacks. And with the Hyoton, he could create ice - based jutsu that are much more powerful than normal ice jutsu, like freezing an entire area instantly.
Naruto might gain the ability to tap into a primal energy within him due to his wrath powers. This energy could allow him to heal faster when injured in battle. Also, he could have the power to influence the emotions of his enemies. When they look into his eyes during his wrath - filled moments, they could be filled with fear or hesitation. Additionally, his physical attacks could carry a sort of 'wrath - curse' that weakens his opponents over time as they are continuously exposed to his wrath - powered strikes.
The cat could have the ability to sense chakra. Just like how some animals in the Naruto world can detect danger or the presence of others through their natural instincts, Naruto's cat might be able to sense chakra levels, which could be helpful to Naruto in various situations.
He could have a summon - like animal as a pet. For example, a toad that he befriends and keeps as a pet instead of just using for summons in battles.