Rikoudou jutsu is the 6 paths something that ms obito obviously cannot use. Izanagi if we translate it as the kinjutsu madara showed obito then yes he knows this however we do not know for sure if 14 year old obito gained another sharingan eye to waste izanagi on. The spare sharingan's at his hideout is most likely free sharingans he got from the massacre. Its very likely and almost certain that 14 year old obito fought minato with 1 sharingan, unless before madara died he transplanted his 1 sharingan to obito which is unknown. Regardless if we are pitting naruto in that same situation, he use techniques demonstrated by that obito and not current obito
Why will Madara learn something to Obito if he can't use it? It's not as if Madara knew Obito would have the rinnengan after since Nagato was the one supposed to revive him. Furthermore i do think it's highly possible that he took Madara's Sharingan. Why leaving that there? Also i don't agree with the fact that the Obito should only use what he has displayed against Minato. What you don't understand is that in the fight between Obito and Minato, it was a battle of speed, and it's only for that reason that neither used range attacks, because they knew it would be useless(Minato mentioned the fact that he needs to trade hits with him, Obito needed chain to restrict him because of his speed). It doesn't mean that against another opponent, they would use the same move. That was only adapted for that situation
It wasn't too long before obito awakened the ms and when he attacked the village. Next is that current obito has another 15 years with kamui, its obvious he has gained better mastery of this and we have seen this when he is able to wrap fuma shurikens out of his dimensions but also use katon justus like rambo in conjunction with it. Not to forget that current obito was able to block zabuza's sword with one hand something that 14 year old obito couldn't do and evidence of this is when he coundnt even punch his way out of madara's hideout.
Juding by the difference between the Kakashi in Kakashi Gaiden and the one in that flash-back, i believe 2years at the very least past since that moment. We've seen that Obito directly managed to completely master the phasing when he was facing the Kirigakure ninjas, he even directly mastered the mokuton sashiki. All that was to show us that Obito is a quick-learner. Zetsu even said he now understand why Madara chosed him. So i believe that 2years is more than enough for that Obito to have completely mastered and know all the different ways he could use his kamui, especially when Madara considered that if Obito was behind everything, he was sure that the plan was good, meaning that Obito was already highly intelligent and skillfull since back then.
He may have learn more combos with the time, but in his kamui skills, i personally believe it was already at the top. Not because we've not seen him use inverse kamui that he wasn't able to. He didn't use it against Minato not only because the fight didn't last long, but also because like i've said, range attacks weren't that suited for that situation.
Even when we talk about current Obito, he has never shown the inverse kamui even when fighting Danzo's bodyguards, or Konan and even in the fight against Naruto and co, we only saw it much more later in the fight, so it's not because we've not seen him use it against Minato that he wasn't able to. Just look at Kakashi currently and he is a non-Uchiha, so more difficulty to handle his eye technique and he only had kamui for 1year or so, but he can already use inverse kamui or other skills.
Even with no knowledge naruto always starts with kage bunshin, which the sharingan cannot distinguish. Obito would have to be certain that the person he is warping is the real naruto otherwise during this stage he is open to attacks. Now image several bm clones, km clones and sm clones. All these clones have great perception ability and speed. If obito makes a slight mistake he will eat a fuuton shuriken rasengan. Obito cannot keep on evading all these many forms of naruto for teh whole fight. If it comes down to it naruto can summon ma and pa frog for gamarinsho, a technique that not even kamui can evade (unless obito warps away, but then in that case its a forfeit) and when paralysed, he is therefore the taking. To think 14 year old obito beats current naruto is very unrealistic.
I don't see Naruto summoning those guys since it's not really his fighting style to begin with. It's more like Jiraya's fighting style. Just to make you remember, Minato can summon as well, but he didn't against Obito. I don't see where it's far-fetched to believe that he could beat Naruto when he has shown the skills necessary for that even back then
EDIT: Id like to continue this however ive something else to do but current naruto mops the floor with 14 year old obito. He however doesn't have a way of getting rid of the kyuubi though he can match its power and even overwhelm it, you also forget that naruto's clones in the war have been all over the place, surely he can limit the damage done to the village with these bunshin spams and infact he can leave a few bm and km and perhaps sm clones to fight 14 year old obito whilst he takes on the fox. He is a one man army after all
Ok no problem
I think you underestimate a lot Obito from back then though. His kamui use was already perfect and it made him difficult to counter. Someone like Naruto who isn't really that analytic could fail against this jutsu. We've already seen how easily Obito could capture him in close combat just with his kamui use. Hell even a crippled Nagato was able to capture him
Also, what even stops Obito from summoning directly Kyubi to help him against Naruto if needed?
