Some things I've put some thought into.

Replace subs reward of 10,000 lvls to a kekkei genkai (not doujutsu).

add a 0.00002% of when someone makes a Juubi a Kaguya option pops up or a Raw juubi which is the form obito sucked into himself.)

Sealing jutsus for kages to seal bijuus into people from themselves.

Jutsu combination system. Pick 2 jutsus and see if they combine. (elemental rasen shurikens , Amaterasenshuriken , Arrow with yasenka (sasuke ms in crow) , etc.)

EDIT: You can with Sharingan Copy, but only Hatake.

EDIT: Done, but only for one combination.

EDIT: Done, but seems that only few people know how to get it.

a VERY VERY small chance for a Rikudou character to be born with potential of Eye Of The moon , must attain mangekyou sharingan and byakugan to fuse all 3 to make eye of moon. (3rd is their rinnegan)

Danzo clan?? A clan that has multiple lives using sharingan which you extract from uchihas , profound in wind style and is devious.

The highly suggested REBIRTH but instead of you keeping everything , lvls , jutsus etc. You lose all ur stats but keep all doujutsus , jutsus , taijutsus etc.

A Secret forbidden jutsu only few will know the location of... The Chimera technique.... Fuse your body with others giving you their jutsus and doujutsus to wield as your own , VERY DANGEROUS!

I got jutsu Ideas but there is too much to put here so if you want them contact me on my pager , Pumpedhero. Yami you know me :>

Iburi Clan.. The clan of smoke people.. they lived under the hidden leaf and as I said, can turn into smoke.

Kurama Clan A very skillful genjutsu clan due to their kekkei genkai, every generation one is born so skilled that they can kill their opponent with genjutsu.

Tsuchigumo Clan , A clan that posses'd a jutsu to wipe out an entire village , similar to the jutsu known as "Shinra Tensei".

My last and 1 of my most favorite that I'd like to see is kinda custom.

Sasori clan Clan to make artificial puppets or puppets from human corpses that specialize in what they are built for.

I nominate myself for president

I nominate Bosha for president