Originally Posted by Numinous
Pardon, can you provide me a panel with EdoMadara with a non-Rinnegan doujutsu after he used Rinnegan for the first time? Only then you can say he can switch around.
Actually I didn't find him switching them after activating them...other than maybe he is deciding to use the Rinnegan continuously... He is using all the dojutsu's in one eye set. Obito is unable to do that due to him not naturally having that evolution take place..so he has to use the pair of SG+RG. Nagato never had another dojutsu so he wouldn't be capable of switching around. so right now you're correct until proved otherwise..