Fu could use her healing abilities. If Sakura is attacking Naruto with some kind of harmful jutsu that causes internal damage, Fu can use her healing powers to counteract the effects. She could also transfer some of her own life force or energy to Naruto to keep him alive and stable while dealing with Sakura. This would be a more spiritual or mystical way of saving Naruto.
Perhaps Fu has some sort of mind - control resistance ability. If Sakura is using a genjutsu or some mind - influencing technique on Naruto, Fu can break the connection. She can then turn the tables and use her own genjutsu on Sakura to make her forget about Naruto or at least stop her from harming him.
Well, in some fanfictions, Fu might use her unique jutsu skills. For example, she could create a powerful barrier to protect Naruto from Sakura if Sakura is somehow being controlled or acting aggressively. Fu's ability to manipulate nature energy could also play a role. She might use it to disorient Sakura or make her lose her focus on Naruto.
One way is through brute force. Houndoom could be extremely powerful in the fanfiction and simply overpower Naruto's attackers. For instance, if there are some assassins after Naruto, Houndoom could charge at them and knock them out with its physical strength.
One way could be that Naruto uses his Sage Mode. In this mode, his senses are heightened, allowing him to easily detect the location of Moegei and the kidnappers. He can then quickly move to the scene and overpower the kidnappers with his enhanced strength and speed.
Often in fanfiction, Naruto moves on from Sakura when he experiences a major event. Say, he nearly dies in a battle and has an epiphany. He realizes that life is short and he should focus on things that truly matter. His feelings for Sakura seem less important compared to his newfound understanding of life, and so he moves on.
Maybe Sakura is being controlled by some dark force and is about to harm Naruto, so Gaara steps in to save him.
He could use his sand powers to create a barrier between Naruto and Sakura.
One way is that he could use his super - senses to detect any flaws in the fanfiction's plot. Then, he can somehow communicate with the writer (maybe in a magical way) to suggest improvements. For instance, if there's a lack of action in the story, he can inspire the writer to add some of his signature acrobatic fight scenes.
In some fanfictions, Naruto could gain the ability to fly as a result of a forbidden jutsu. This jutsu might be so powerful that it not only gives him flight but also enhances his other abilities. For instance, he could be forced to use this jutsu in a life - or - death situation against a very powerful enemy. Also, he could fly if he absorbs some kind of special energy or power - up from an ancient relic. This power - up could transform his body in a way that allows him to fly, like growing wings made of pure chakra.
Well, Naruto has a strong sense of justice. He can't stand to see anyone being bullied, especially someone he cares about like Sakura. He might also want to prove himself. By standing up to the bullies, he shows that he's not the weakling some people think he is.
In many fanfictions, Naruto might use his ninja skills. He could suddenly appear and physically stop the bullies. For example, he might use his Shadow Clone Jutsu to surround the bullies and intimidate them into leaving Sakura alone.