1. Zetsu has been watching Might Guy's battles and knows that he forgets who he fights(hence why tobi mentioned that) and the akastuki has information on Hatake Kakashi for sure..whether it's because of Orochimaru's or Itachi's involvement with the anbu black ops, they knew what type of life he had, hence why he said "you're living a life of regrets" well, what the hell does kakashi regret? Failing to save Obito, rin, and blames himself for the loss of his sensei... that he couldn't protect his comrades is his biggest regret. The akastuki have the means to know that much.
2. Obito would probably not have existed nor been withing proximity to the mizukage OR fight minato to be logically explained somehow differently, it doesn't add up for shit as it comes to Obito's whereabouts...
3. You're wrong buddy. saying Obito is Tobi is failing any type of logic that might exist, Obito for starters has no motive to do this, Obito liked fighting and he would have not wanted to kill the Uchiha in the First place...
FFS, IT DOES NOT ADD UP, SAYING HE'S OBITO CUZ HE KNOWS MIGHT GUY AND KAKASHI IS FLAWED LOGIC...
NOT to mention, almost everyone knows of "Kakashi of the Sharingan" and Might Guy ass the guy who beefed kisame, and forgot his name a couple times in the past...
as for kagami, more likely... but it could also be a person from the Senju Clan who was there when hashi/madara shit was going down... people think it's an Uchiha, but it can POSSIBLY be a senju as well (doubt we'll know for a bit with kishi's plot no jutsu...
I am enjoying this.
1. On kakashi's information, that is an extremely loose case and relies on the fact that they either tailed all the anbu or just particularly strong ones. Or it could have been becuase he was with the nine tails. It still relies on the fact that kakashi has said this information, tho, which I don't think he did. I think that the fact this whole team died is something that easily attainable information. Knowing how much he feels responsible for all of it is not an easy conclusion to jump to, especially because we don't kno how rin died and in the ninja world, people die on missions all the time. It would be a huge step for tobi or zetsu to take to say he feels it's his fault that one of his partners died without zetsu having heard him say it (possible but unlikely) or an understanding of exactly what happened that day. If zetsu knew that, he would have to be there, but obito was there, and kagami would kno nothing. It could go either way and the way you are arguing it makes it a mute point, because although it's not probable that zetsu got this information, it's plausible and so it cannot be eliminated as an option. It's also not probable that zetsu tracked kakashi instead of anybody else, because there has to be more important targets than him. But again, improbable but plausible, so I'll put that point aside for now. Onto guy, it's just too improbable that both zetsu brought up such a non important piece of information to their fight, nor is it probable that he remembered it. Zetsu wasn't on the island with naruto and guy, so he didn't kno about that situation when guy forgot him again. That means that it only happened once (or maybe twice, I don't remember another time besides when team guy fights kisame when gaara was captured) in tobi's and zetsu's recollection. Why would zetsu bring it up if it only happened that one time? And why would tobi remember that one fact, from a while ago, back when the akatsuki was alive. And then why would tobi declare that he had a tendency to forget peoples faces? Unless you count when he was fighting those three guys (I forget their names) and you think zetsu was again for no reason tracking guy, whom he truly has no reason to track. Under that logic tobi would have no reason to say that guy always forgets peoples faces having only 1 recorded situation of it happening. He would need more experiences with it in order to jump to such a conclusion. And on a larger scale, why even bring up such information? If he were obito, he would at least have a relationship as former peers to go off of, a reason to speak only to them. If he were kagami he would have no relation and therefore no reason to single out those 2. Where were the random facts about killer bee? He could have definitely brought up naruto's brashness and his inability to even save sasuke. But no. He only talked to the 2 most insignificant members of the battle about to erupt. Because let's face it, they can't be of too much of a threat, except for maybe they could fight tobi and naruto and bee would fight the ten tails. I digress. The point is, they are not a threat to his plan, bee and naruto are. So why talk to kakashi and guy? Why even bring up that fact about guy? It doesn't even effect guy for him to say that? It's just not very practical today such things for no reason, especially if you say them to people who mean nothing to you. It is much more likely that obito would say this then that anybody else would.
Oh and by the way everybody has heard about kakashi the copy cat ninja, but nobody knows his back story.
2. Now we are getting into arguments I'm more familiar with. Mizukage was controlled after his attack on the leaf village. He could have definitely gone to the mizukage as a part of the plan that madara and him had created, and that's that about his whereabouts with mizukage. He definitely existed then. And against minato, he was able to compete against him only until he lost the element of suprise. All he used was space-time ninjutsu the whole time. The fact that he is untouchable allowed him to go up against whimsy minato and allows him to go up against anybody. As soon as minato learns all he needed to know about the jutsu, however, he easily counters it. If you look at the situation, after that tobi truly didn't stand a chance. He was not better than minato, he just has a really kick ass jutsu that nobody except minato and konan has figured their way around. Konan would have won had it not been for izangi. We don't even know if tobi has any real fighting skill. All he really has needed is to be intangible and the abilities of his sharingan, and that as we've seen makes an extremely dangerous ninja. I don't know what you mean by obito's whereabouts don't add up, but his time in konoha was like 3 hours at most, and then he was gone. And he can teleport literally anywhere in the world almost instantaneously. His whereabouts add up alright.
3. There is some logic behind it. What motive does kagami have? Every single option for who he is except for maybe izuna (who it definitely isn't) has no motive to do any of this. Only madara uchiha has a hatred of the uchiha clan, because they turned their backs on him and stayed with the village. No matter whom tobi turns out to be, he was definitely talked into becoming tobi, because I bet that madara along with his sharingans ability to influence decisions could persuade someone to join his cause, especially after aging their life. And when you have persuaded somebody as far as essentially being your incarnate, they will probably do what you will. Madara wanted revenge on the uchiha, and tobi did that for him. Speaking of which, does kagami have a reason for needing to be reconstructed with white zetsu like material? Because obito was crushed by boulders and would therefore need to be reconfigured. To our knowledge kagami's body was perfectly fine. I think it's a stronger argument to say that the one who was crushed by boulders that we saw would need such reconstruction then to say that even though he was perfectly healthy, at some point something happened to kagami and he needed the whites zestu material for it.
I'm not saying he is obito because he knows guy and kakashi, I am saying that him knowing guy and kakashi strengthens the argument that the is obito, because obito would probably know guy and would definitely know kakashi. I just didn't give the entire obito argument when I brought up supporting evidence and so you considered it to be my main evidence, which is not the case.
I don't know where you got that everybody knows that guy beefed kisame, because while zetsu and so maybe tobi knew, nobody else probably found out about it. Some people might know kisame, and some people might know guy, but nobody except for zetsu is just gonna find out that guy forgot kisames faces, and not even he imo would care about it.
Your senju idea is possible, but there isn't much evidence to back it so I'm not gonna argue it.