Well I have some ideas, however rough they may be. However I am still going to post them and hope that everyone will help me refine them.
So most already know of the first, and only stage, of the Hyuuga's in game abilities, however I was thinking that it could be structured similar to the Uchiha and Sharingan. i.e.
Byakugan (2)
Enhanced Byakugan (4) plus lose of two charm points. Now the enhanced Byakugan would act much like the Sharingan and Magneyko Sharingan and become a perma-buff upon activation and as such incur similar style buffs as the Uchiha, however it would be with whatever Neji has already programed the Byakugan to do. Also, with each reset the percentages for this buff would also increase similar to being an Uchiha and this version would be available after being reborn into Hyuuga twice. The Enhanced Byakugan would also first be able to be activated at the same amount of dks as the Magneyko.
Now for the techniques, I feel that Hyuugans already have a decent amount of technique's but that they should gain a, well coup de grace you could say. My propsal would be to include Hakke Sanbyakurokujūichi Shiki, or Eight Trigrams Three-Hundred-Sixty-One Palms. Now as for what it would do, well obviously it performs 361 hits to the opponent and I believe it should only attack a single opponent at a time. Now each hit should cause damage in proportion to the amount of resets have been put into being a Hyuuga, i.e. second reset causes 1-4 damage per hit, third causes 3-6, and the fourth causes 5-8. Also it should cost maybe 6 chakra?
My last thought is that to fairly counter the continuous loss of charm points caused by the activation of using the Enhanced Byakugan would be to, when the Enhanced Byakugan is activated, provide a free pass with Hinata. i.e. During the Hinata event, when she sees you she immediately notices your doujutsu and becomes curious as to how you have become so proficient in its use so naturally you 'spend a few hours of converstation with Hinata in the forest.'
Well that is all I have, so now comes the comments and criticism.