Two Naruto Crossover Ideas
Disclaimer: As usual, I own nothing involved in either of these.
AN: This is one of the few times where I'm not going to attempt to write a mini-prologue, since I really just wanted to put these down in case someone wanted to use them. I really am not well enough versed in Naruto canon to attempt either at this time because quite frankly, I could never get into the actual Naruto anime and manga. I've enjoyed a few Naruto-crossover fics, and I just couldn't not put these down since they were intruding on me writing the stories I'm actually working on. I'd enjoy reading either of these ideas expanded, even if just the basic concept. I'm adding in the details in a rough outline of how *I* would write them.
Idea One: Naruto + SM
This is more of a character concept rather than a fleshed out story idea. It is mostly born out of something I found strange when hearing about Naruto. The Kyuubi is seen as an unstoppable force of destruction, and while feared, the other bijuu seem like they were easily sealed away when the other countries wanted to seal them. To the best of my knowledge, there is no backstory of Shukaku or the Nibi going on massive unstoppable destructive sprees before they are sealed away into their relative containers. This story would attempt to explain that. The basics would be that after Galaxia's defeat, the reincarnation of the Senshi gets knocked off course. Time would pass and the senshi do not reappear and the world evolves, eventually leaving us in the Elemental Countries. Eventually, each senshi line is reincarnated within the ninja world, probably as bloodline users, all except Saturn whose power was consumed by the Kyuubi which would explain why of all the Bijuu, the Kyuubi is especially feared and extremely powerful.
The only scene I've thought of would be the awakening of Saturn's power. During the battle on the bridge during the Wave arc, one of two things would happen during Naruto's fight with Haku. First, Haku could get stabbed through the chest trying to protect Zabuza and Naruto, in seeing one of the few people to ever treat him decently, would wind up falling into his mindscape, find Hotaru and help her finish subduing the Kyuubi and agree to take her power to save his friend even at the cost of his masculinity since a male cannot channel a planetary mana connection properly. The other option would be that Naruto and Haku's fight drifts in the way of the Chidori or perhaps the fight in general between the two older ninjas, resulting in Naruto being severely injured (possibly Haku as well) and Naruto making the same deal with Hotaru to survive himself (and possibly to heal his friend) again at the cost of his masculinity. The seal on Naruto's belly would flash brightly and start disappearing, which would cause Kakashi to really freak out but the symbol for Saturn would appear on Naruto's forehead and in a flash of light, he would transform into Sailor Saturn and fix the situation. Saturn would turn her glaive on Gato's men and demolish all of them with a Silence Glaive Surprise before passing out.
I'd imagine that Naruto would have fused features. He would either resemble Kushina more or keep his resemblance to Minato, but with subtle changes. There would be a purpleish cast to his either blond or red hair, his irises would gain a purple hue or outright shift color and his body would clearly be female though more along the lines of a kunoichi than Hotaru's rather frail body. She would also gain all of Hotaru's memories from her previous incarnation, along with the same semi-memory of the Silver Millennium that all the Senshi had and her personality would have to be mixed slightly between Naruto and Hotaru. She would keep her Senshi abilities mostly under wraps. They would be a clutch move when nothing else was working. Besides, she would suffer from Saturn's biggest weakness, that she is just far too powerful to constructively use her moves. Saturn's weakest attack can demolish city blocks or annihilate small armies… not exactly conducive to fighting around allies. I would imagine that the fusion person would take on either the name Hotaru Uzumaki (which I would favor myself) or Naruto Tomoe.
As for the other senshi, the only one that I've thought about is Mercury. I could see one of two people working for it, either a female Haku (ice power bloodline would work) or Hinata (features, shy personality and highly precise form of combat would work). I'd probably have to go with female Haku myself. As for relationships… well, I cannot imagine Naruto falling for a male, and would have to imagine her winding up with one of the other senshi once they are discovered.
As for long term plot… the upshot of Akatsuki would be working with demons, possibly with having an escaped Jedite from his crystal prison replacing Madara as the true villain.
Idea Two: Naruto + Slayers
In Season 3 of Slayers, a barrier surrounding the known world comes down and allows people to travel beyond it for the first time in recognized history. To my knowledge, in the Naruto-verse, people do not travel beyond the sea. The idea would be that the Elemental Countries would be an opposite continent from the barrier countries and after Slayers Try is over, the crew decides to accompany Amelia on a diplomatic, first contact mission for Saillune to the Elemental countries. They find a small, abused Naruto after he escapes the Kyuubi festival mob when he is still a child and decide to take him in.
Tentative trade/connections between the countries are established between the Elemental Countries and Saillune, and the delegation + Naruto returns home. Amelia uses white magic to either cleanse or release the trapped mazoku from inside Naruto. I'd personally write a female Kyuubi as being released and realizing that these people could A) hurt her and B) she's actually a lieutenant of Beastmaster Zelas and is Xellos' mate who was cut off from everyone when the barrier went up. In fact, I'd probably write all of the bijuu as being some of Zelas' stronger servants, as gigantic animal demons would fit the bill there. However, without a connection to their progenitor, they all went feral. The bijuu/mazoku would become strikingly intelligent.
I'd probably write Naruto as being adopted by the group as a whole, learning sorcery, some swordplay and some shamanism from "Auntie Lina, Auntie Amelia, Uncle Gourry and Uncle Zel." "Auntie Kyuubi (would have to find a fitting name, since Kyuubi is a descriptive rather than a true name) and Uncle Xellos" would appear to make trouble from time to time.
Naruto would eventually return to Konoha to learn about the land of his origins, perhaps involving a quest to bring the Slayers back to the Elemental countries. Beyond that… I haven't thought further.