Why are some people able to use the abilities of a Transplanted MS while others apparently can't use it? Like we saw 7 cases where one got transplanted. Izuna to Madara, Obito to Kakashi, Shisui to a Crow, Itachi to Sasuke, Random Uchiha and Shisui to Danzo, Random Uchiha to Obito and then Kakashi/Obito to Madara. I always thought just like the Rinnegan abilities they would not be able to be used if they get transplanted. Since we never saw what ability Madara or Izuna have they don't really help here. Obito only used the other Sharingan to not get blind on his own. Sasuke also wasn't able to use Tsukuyomi. The Shisui to Crow one could be argued it is because of the Transcription Seal that was used but still the Crow is somehow able to use Kotoamatsukami but I wonder why Danzo on the other hand wasn't able to use the other Eye from Shisui. But on the other hand Kakashi is somehow able to use Kamui after some years and Madara after some seconds after he stole it from Kakashi. Is there any explanation for why this is the case that I missed?
The rules appear to be as follows: Standard transplant: you have the ability that was already embedded in the eye. Eternal mangekyou transplant: your innate abilities override the embedded ability in the eye as part of the EMS transformation.
So basically Danzo could have been extremely broken if all eyes have been an MS