Naruto, Minato, & Kakashi vs. Obito
Now we all know that this fight is bound to happen once the 4 hokages arrive on the battlefield, but after thinking I've kind of thought of a simple strategy as to how Naruto, Minato, and Kakashi can take down Obito.
To start off, Minato would run towards Obito, with Naruto running behind him, he would then throw his FTG kunai at him like he did last time.
Now if Obito is not dumb, he would recognize this old strategy and try to counter it by simply absorbing the kunai with his Kamui. Then, Obito would think that he would have Minato in his grasp so he would then either try to grab and absorb Minato, or attack him head on with one of his Fire or Wood Style jutsu or projectile weapons. But Obito wouldn't be able to even touch him because Minato could just simply instantly teleport to the kunai that Obito sent to the other dimension.
Then immediately after Minato teleported to the kunai in the other dimension, Naruto, who was right behind Minato before he teleported could quickly launch a chakra punch that Obito would obviously phase through.
Then of course, the body part that was phasing through the chakra punch would be sent to the other dimension, giving Minato a quick opening to attack Obito with a devastating Rasengan like he did last time.
This would of course affect Obito in the outside world.
This would incapacitate Obito long enough for Naruto to attack him with his own Rasengan, thus taking down.
Then after that, Kakashi would use his own Kamui to bring Minato back based on what he did in these two panels.
But at the beginning, if Obito was actually dumb enough to let the kunai phase right through him like last time, this would still put him in a corner, because Kakashi would then be the one to send the kunai to the other dimension with his Kamui. Then of course Minato would teleport to that kunai, Naruto would attack Obito with chakra punch that he would obviously phase through, giving Minato an opportunity to attack Obito's body part with a Rasengan from the other dimension. And again, this would leave Obito incapacitated long enough for Naruto to attack him with his own Rasengan, thus defeating him, after that Kakashi would then bring Minato back to the real world with his own Kamui.
Now for those who think about bringing Obito's Rinnegan into this scenario, don't bother, because Obito himself has a very good reason why he's not using the Rinnegan and this video right here explains it perfectly:
Now I could be completely wrong about all of this, but this is how I picture the fight going down. Tell me what you guys think.