I've seen all of naruto and know alot about it, but theres always been that one thing I could never figure out, how exactly does edo tensei work? Like its never been explained to deeply or specificlly on how powerful it makes the edo summons, how much chakra it takes for each summon, we got clues and vague stuff at best. Personally, I have a theory for it...

The summoned edos strength is dependent on how much chakra the summoner puts into it, however, it takes very little chakra to summon each individual. This makes sense, since Kabuto, a ninja with average reserves, summoned all the edo in the war. If it really took alot of chakra to summon each individual, kabuto would not have been able to pull it off since he doesnt have much chakra. So it must really take very little chakra to summon an edo, no matter who they are. The summoned edos strength is dependent on how much chakra the summoner puts into it, this is evident by how back in part 1 orochimaru summoned edos and were stated to be far from there full power, but in the war all his edo summons were stated to be almost at full power. If its true that it takes very little chakra to summon each edo, then this means that if an edo is far from their full power its because not enough chakra was put into it. for example, if orochimaru summoned an edo and it was far from full power, it means that it took very little chakra to do so, say 5 units of chakra for the summon. But if orochimaru summoned that same edo and it was instead at full power, it means it took more chakra to do, say 10 units this time. But in both scenarios, it took very little chakra to summon the edo. In other words, this would mean that regardless of how much chakra it takes to summon an edo, it will never take a lot to do so. Also, when an edo says they arent at full power, it means that they dont have access to the same reserves as when they were alive. This makes sense, since its been explicitly stated that edos are weaker than their living selves, however we see that this simply cannot always be the case as edos can be summoned at near full power, so clearly that can be taken up a notch to full power. Also, notice how in part 1 when orochimaru summoned edo hashirama and tobirama they were far from full power, but in part 2, orochimaru summoned hashi and tobirama, minato and hiruzen all near full power. How can this be? Well, orochimaru, for one, didnt have access to his full reserves when he summoned them in part 1 because he was: 1) just fighting hiruzen, which lowered his reserves alot and 2) Hadnt perfected Edo tensei, which heavily implies that even if he had his full reserves, the technique itself wouldnt have allowed him to summon the edos near full power or much greater than what he did. In part 2, oro had his full reserves when he summoned the edos, and he had also perfected edo tensei, which makes sense, since he now was able to summon hashirama and tobirama, PLUS minato and Hiruzen at near full power. When kabuto summoned all his edos, all of them were stated to be far from their full power, this makes sense since even if he did have the reserves to summon them since it takes very little chakra to summon an edo, he still didnt have the reserves to summon them at near full power or full power. This is because while it takes little chakra to summon an individual, the amount of edos kabuto had summoned was huge, which all added up. so yes kabuto had enough chakra to summon a huge amount of edos, but not enough to summon ALL of them at full power.

I believe what is meant when its said that edos have "limitless chakra" , is that there chakra regenerates over time, however slowly. This is evident by many things, and is believed to be true by many people. but heres an example:

When Edo hashirama was helping the other hokages keep up the red barrier, not only was he pooling his chakra into a barrier, but that very barrier was literally restriciting the freaking ten tails itself. This barrier could not have been any ordinary one, since it was enough to restrict the ten tails, and it was literally stated that it takes kage class ninja to make and keep up. Anyways, while keeping up the barrier, hashirama literally was only able to make a few mokuton clones. That right there proves that edo tenseis chakra doesnt regenerate quickly, let alone instantly.

Now after reading all this, some of you might be wondering how this thoery can be true, if Edo Madara, who was summoned no where near full power, was able to stalemate Edo hashirama, who was summoned at near full power, and we know that alive hashirama wasnt much stronger than alive madara was. Well, you have to consider that Edo Hashirama was lower on chakra at the time then edo madara was when they fought, this is because hashirama was doing alot more harder fighting much more recently than edo madara was.

So, after reading all this, assuming any of you actually read all of this and understood it, what do you think of my theory?