To unlock Rinnegan you may need EMS eyes

[The Demon Hawk]

See I understand your theory for debunking 1, but there is no proof.
All we know is that Indra + Ashura is required. Obito had Indra + Ashura but didn't have EMS. Son what the OP may be trying to suggest is that is EMS an essential requirement even if person has Indra + Ashura, as Obito did ? Do we have any proof debunking this? Was there any person who had EMS + Indra + Ashura and did not awake Rinnegan? No.
Likewise there is no proof that if a person obtains Indra + Ashura at MS stage and is Indra transmigrant, he would awaken a Rinnegan. So we cannot even say that EMS could be bypassed.
So we are at a point where both theories would do. I don't see any reason for rejecting one.

Actually, to awaken the Rinnegan, Sage's chakra is required (from what we know). It can be obtained by combining the chakras of Indra's and Ashura's transmigrants, not just any of the descendants. Obito had Ashura's chakra, but he didn't have Indra's chakra. So basing your argument on Obito is futile since he had neither Indra's chakra nor the EMS. So from this, we can't conclude what was the reason that Obito didn't awaken the Rinnegan. Was it because of not having Indra's chakra or because of not having EMS, or both of the above.

@bold That's where your argument gets flawed. Obito did not have both chakras, he only had Ashura's. Are you mixing having chakra of descendants with that of transmigrants? Since they are both very different.

@underlined You're right! That's what I'm trying to say as well. But keep in mind the difference between the chakras of transmigrants and descendants. And then the implication of that sentence will also be correct. That's why I'm saying that concluding the result considering Obito's circumstances is useless since he didn't have 2 out of 3 requirements.

You're right about your last point. Whether EMS or MS or even the Sharingan could be enough. But to unlock the Rinnegan, you need Sage's chakra (could be Indra + Ashura chakra) and could be one of the Uchiha eyes (EMS, MS or Sharingan). That's a given.