I am going to be arguing whether Hiruzen did truly fight against the two previous hokage at full strength.
In the latest chapter, we finally get to see what the real Hashirama and Tobirama have to say. The first time Orochimaru resurrected them, they were "mindless zombies" due to the suppressing talisman. However, this time, that is not the case. All the hokages have full control over their thoughts and emotions. With that being said, Tobirama states that Orochimaru has brought them back THIS TIME with almost all their strength.
Through this, we can conclude that it is very quite possible that the previous time that Orochimaru summoned the two kages, they were not at 100% power. Furthermore, this time, we can also see that Hashirama and Tobirama were able to break free and partially break free, respectively, from the Edo Tensei.
As stated by Orochimaru, Hashirama is not fully under his control. By this token, we can conclude that not only is hashirama stronger this time, but since Orochimaru has his cells, even the sealing is stronger, since it was able to fully stop Tobirama (who was very confident in being able to break free). Having said this, because the seal is stronger this time due to the Hashi cells, the entire Edo Tensei must be as equally strong as well. Additionally, as stated previously by Tobirama, him and the subsequent hokages have been revived almost to at their primes (ie: strongest, as stated in the link above). If we know for a fact that Edo tensei is stronger this time and hashirama was able to challenge its bindings unlike last time, wouldn't it mean that Hashirama must have been summoned at full strenght this time, as well as the other hokages?
If all this evidence isn't enough, there is also the entire scene with Tobirama basically petrifying Orochimaru with his sheer chakra force, just by lifting a finger, a feat that was NOT achieved in his earlier appearance in the story line.
Hopefully, we can all see that the first time the First and Second were revived, they were not at full strength. This time however, we know almost certainly, that they are. Due to all these points that I have stated, this ultimately illustrates that Hiruzen did NOT fight them at full strength. Furthermore, the "Professor of Shinobi" (Hiruzen), has been undermined by the "God of Shinobi" (Hashirama) by a very reliably powerful figure: the Sannin Orochimaru.
I hope you agree with me, and I would love to debate over this with anyone
remember this is my opinion and I do not want to start a flame war. I just compiled a bunch of evidence together in hopes of solving this mystery 
Enjoy.
In the latest chapter, we finally get to see what the real Hashirama and Tobirama have to say. The first time Orochimaru resurrected them, they were "mindless zombies" due to the suppressing talisman. However, this time, that is not the case. All the hokages have full control over their thoughts and emotions. With that being said, Tobirama states that Orochimaru has brought them back THIS TIME with almost all their strength.
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Through this, we can conclude that it is very quite possible that the previous time that Orochimaru summoned the two kages, they were not at 100% power. Furthermore, this time, we can also see that Hashirama and Tobirama were able to break free and partially break free, respectively, from the Edo Tensei.
You must be registered for see links
As stated by Orochimaru, Hashirama is not fully under his control. By this token, we can conclude that not only is hashirama stronger this time, but since Orochimaru has his cells, even the sealing is stronger, since it was able to fully stop Tobirama (who was very confident in being able to break free). Having said this, because the seal is stronger this time due to the Hashi cells, the entire Edo Tensei must be as equally strong as well. Additionally, as stated previously by Tobirama, him and the subsequent hokages have been revived almost to at their primes (ie: strongest, as stated in the link above). If we know for a fact that Edo tensei is stronger this time and hashirama was able to challenge its bindings unlike last time, wouldn't it mean that Hashirama must have been summoned at full strenght this time, as well as the other hokages?
If all this evidence isn't enough, there is also the entire scene with Tobirama basically petrifying Orochimaru with his sheer chakra force, just by lifting a finger, a feat that was NOT achieved in his earlier appearance in the story line.
You must be registered for see links
Hopefully, we can all see that the first time the First and Second were revived, they were not at full strength. This time however, we know almost certainly, that they are. Due to all these points that I have stated, this ultimately illustrates that Hiruzen did NOT fight them at full strength. Furthermore, the "Professor of Shinobi" (Hiruzen), has been undermined by the "God of Shinobi" (Hashirama) by a very reliably powerful figure: the Sannin Orochimaru.
You must be registered for see links
I hope you agree with me, and I would love to debate over this with anyone
Enjoy.