Suggestions.

Akatsuki

1) Hanzo is still leader of Amegakure, but he never rusted and never stopped to fight regularly. Maybe he is even willingly allowing Akatsuki to work in Amegakure and is loosely allied with Yahiko, as Yahiko would rather not defeat Hanzo IMO and they cooping is better than letting this blow with Danzo's help.

2) Ame Orphans were taken under care of Hanzo and trained, Yahiko and Konan still have their abilities and Yahiko became Hanzo's right hand.

3) After a shady talk with Danzo, Yahiko and Hanzo came with idea to create Akatsuki, whose original purpose was similar, yet different, to Root: They were to act as spies and due to terrorist acts undermining strength of Major Shinobi Villages.

4) After some time with successful spies, Yahiko started to recruit shinobi from other villages into his organization, taking shinobi that weren't satisfied with their villages system like Kisame, or were already freelancers like Kakuzu.

Kakashi's Sharingan:

Not long after the Third Shinobi World War finished, Team Minato (who was Hokage already) were sent on a mission to dispose of a missing nin from Uchiha Clan, which killed couple of Konoha shinobi while defecting. When they brought him close to death, Obito came with idea that Rin should implant his Sharingan into Kakashi, so he will be able to complete his Chidori on which he was still working.

The other Sharingan was crushed by Obito, so secrets of Sharingan won't fall in the wrong hands - this part is opened to change by Shadow Moon if he want to make Team Minato bring the dead body with the other Sharingan intact so Danzo could put his hand on it. (You know, "hand" because he have only one). It could fit actually, as Kakashi lacked left eye, while Danzo lacked right one.

Bijuus and Jinchuurikis:

Some of the canon Jinchuuriki were known mainly from their skills gained from Bijuus or were known better overall. Who should remain as such IMO:

1) Kushina with Kurama - obviously, as Kyuubi is way too OP to give it to player and without Madara surviving VotE, there's no way Kyuubi would be released from her at the day of Naruto's birth.

2) Roshi with Son Goku - he was his Jinchuuriki for 40 years when he died in Part 2, his skills were mainly based on his Yoton. While they weren't true friends like Bee and Hachibi, they were tuned.

3) Bee with Gyuki - Similar case as Roshi. While it's possible to kill Yugito Nii, defeating Killer Bee is really hard without OP abilities.

4) Yagura with Isobu - leave him as Perfect Jinchuuriki and current (Yondaime) Mizukage.

5) Gaara with Shukaku - I simply can't see Gaara as anything else than Ichibi's Jinchuuriki, be him as unstable as he was in Part 1 or level headed as in Part 2, even if still feared.

Matatabi (Nibi) [Kumogalure], Kokuo (Gobi) [Iwagakure], Saiken (Rokubi) [Kirigakure] and Chomei (Nanabi) [Takigakure] should be open for the taking, as their Jinchuurikis either have skills that rather do not utilize powers of their Bijuu (Han, Utakata) or IMO have not enough interesting feats to remain with their Bijuu (Yugito Nii - making nails long as claws is likely from Nibi, maybe homing Katon is her own, transforming into full Nibi more or less willingly; Fuu only shown Hiden jutsu that is inferior to Kirigakure as is not filled with chakra and not everyone would be blinded, if she could fly with Nanabi's chakra is unknown).

Uzumaki needs some Sealing Jutsu love, we need feats for them.
Kakashi showing his face.
Hyuuga needs more love too, give the Byakugan a power up.

I accepted Zulkuss suggestion

https://narutoaw.forumotion.com/t9-about-the-rp

I am already thinking of making some sealing jutsu.

Any idea for the battle and stat system?

Well, I want the battle to use dice. Depends on what you and your opponent rolls, your attack may miss,half the damage or even be stronger than normal.

There will be Hit Points (HP) and Chakra system. By default Genin start out with 1000 HP and Chakra. The higher your ninja rank, the higher your HP and Chakra capacity become. Some clan has special ability that grant the ninja more Health or Chakra than normal.

Jutsu consume chakra equal to its rank and some technique has special cost like Shadow clone jutsu which divide your chakra to the clone your create.

About stat. It will follow the Databook style so there will be

Ninjutsu,Taijutsu,Genjutsu,Intelligence,Strength,Speed,Stamina and Hand seals stat. They will affect your battle performance greatly. I will elaborate about that later.