Now before i get flamed im not adding plot no jutsu as an acceptable defeat thats why i said VIRTUALLY.... so lets say i created a blank uchiha member what do we know about him? he has good fire style and the sharingan right? this already puts him on high chunnin level since genjutsu is natural for sharingan users and taijutsu is countered with a sharingan so any uchiha is born with the ability to achieve high chunnin level right off the bat. Now lets say i add another element to his arsenal like wind since wind compliments fire he can now use combination attacks this puts him on jonnin level now the fun starts. This uchiha has killed his best friend and gains MS now we can give him two random MS techniques (we have seen) and sussnno as his 3rd lets say amatertsu and tsukiyomi since kotoamatsuki and kaumi are OP as hell we all agree with that. i suppose we could swap kaumi and amatertsu but it doesnt really matter both have enough power to disable a bijuu which i will get too very soon.. ok now he kills his brother and takes his eyes making all his MS techniques stronger and much less chakara taxing hes beyond kage level now easily.. the 1st ability of the sharingan is too copy ninjutsu so all ninjutsu he sees are usable if they are in his elements.. now he gains the rinnegan through training his ems he can now use ALL five basic chakara natures and with his sharingan any move he sees can be used by him except kekkai genkai (plus his naturally powerful fire release and wind release) this blank uchiha is now demi god level and virtually unbeatable i mean imagine a sussano coated in preta path? the only people who have a chance are kekkai touta users like oniki and muu or high level jinchuricki 7 tails and up.. but muu and onikis techniques can not penetrate preta path so that takes them out of the list and a jinchuricki would have to enter there full bijuu state to fire off a tailed beast bomb powerful enough to harm the sussano in that small opening either amatertsu or kaumi will finish that bijuu off making this blank uchiha virtually more powerful then anyone we have seen in the naruto verse of course this is all hypothetical i wrote this to show all you guys who kishis favorite clan is :scorps:
well first off, not all uchiha can attain sharingan. The databooks have said that along with producing a strong fire tech, awakening sharingan is one of the steps to being considered an uchiha elite, hence if it is a step to beig one of the bst there must be some or many uchiha, including men who could not awaken it. Second...sharingan does not automatically allow you to use stronger ninjutsu, all it allows you to do is copy the hand signs. Even with sharingan it took sasuke several days of training with kakashi to learn chidori, and i could be mistaken but im pretty sure at one point sasuke was shown trying a rasengan but couldnt get it due to the high complexity and chakra control it takes. Last, i wouldnt use madara or even tobi as examples of uchiha with rinnegan because tobi has apparently been around a long time, hence even without rinnegan would have known of the techs and madara could have very likely been given the knowledge of the rinnegans usage upon being altered by kabuto. An example of what im trying to get across is nagato wasnt shown using his rinnegan techs until later...mainly start of the pein arc, so its fairly safe to assume that if he could use them why wouldnt he? so we can guess he didnt have them until a bit later, he was just a chakra tank. That said, unless said uchiha trained with madara or tobi or nagato (someone with knowledge of rinnegan techs) then even upon attaining rinnegan they wouldnt necessarily know how to use them. I doubt if sasuke just unlocked rinnegan that he could spam almighty push immediately, and i doubt anyone else could without massive amounts of training. The only feasable way this could happen would be for said uchiha to go off and train for years in seclusion, but just training and unlocking it is unlikely to give you auto access to the path techniques...not to mention that to obtain the sharingan levels you must undergo massive emotional duress (killing your best friend, killing your brother) so assuming the rinnegan follows a similar styling, the only bigger step to unlocking would be some outrageous massacre that we are unlikely to see.