Madara Uchiha stated that he awakened the Rinnegan shortly before his death and possesses the ability to switch between both it, and his Eternal Mangekyō Sharingan at will. So this imply that the Rinnegan is the final stage of the Sharigan development but if this is true why haven't any other Uchiha been able to achieve such greatness.
1. You only able to activate the Rinnegan with Uchiha/Senju abilities which Madara obtain Hashirama Senju's tissue after his near death battle against him.
2. Or EMS which was only achieved by Madara & Sasuke Uchiha mastery begins to turn into to the Rinnegan: This theory I doubt because the Sage of six paths which was Senju/Uchiha he was the 1st shinobi with the Rinnegan.
Also Kakashi Hatake believed that the rinnegan was merely a mutation that Negato Uzamaki obtain through mere luck; which has been proving to not be true.
1. You only able to activate the Rinnegan with Uchiha/Senju abilities which Madara obtain Hashirama Senju's tissue after his near death battle against him.
2. Or EMS which was only achieved by Madara & Sasuke Uchiha mastery begins to turn into to the Rinnegan: This theory I doubt because the Sage of six paths which was Senju/Uchiha he was the 1st shinobi with the Rinnegan.
Also Kakashi Hatake believed that the rinnegan was merely a mutation that Negato Uzamaki obtain through mere luck; which has been proving to not be true.