So what you guys are theorizing is that Sakura managed to cheat her way into getting sage mode by storing up chakra and thus simulating a large chakra suplly in order to achieve sage mode.
That would be cool, if it werent for the fact that sage mode lasts only a few minutes and it could take days for Sakura to store up chakra. Slug sage mode has never been mentioned in the series, so I doubt it would be now. And also, I don't think it's enough. With Sasuke having Itachi's eyes, he has the strongest ninjutsu and the strongest genjutsu in the world. Not to mention an impenetrable defense. I think that Sakura needs to have learned something and improved upon it to make it her own, much like Naruto did with the rasenshuriken.
Okay so here's my theory. Since Sakura was able to store up chakra. She could have built up 10-20x her normal limit or even more. So she is able to draw in 10-20x more nature energy and balance it out with her stored up energy. What this would allow for is essentially super saiyan sage mode, and it would be one of the most powerful techniques in the series thus far. And the best of all, it would be something only she could have done because of her perfect chakra control.
So their powers would be unique. In fact, at that point the only weak one would be Naruto since he never actually had power greater than sage mode, he just had Kurama's help.
Think you are on to something.
For Sasuke and Naruto it's pretty straightforward. They were trained by one of the Sannin and inherited powerful justsus from their family so they use what they've got.
But for Sakura her only access to Tsunade for power ups.
Heck it can even be a parallel to the sage of the six paths.
We know of him that he was a sage ( so we can assume he knew how to gather natural energy), jinchuuriki and had overpowered eyes.
Sasuke has overpowered eyes.
Naruto has reached the pinnacle of a jinchuuriki.
Sakura's role would be that of a sage. With her chakra control she could surpass Naruto as a sage. No visual indicators that she is in sage mode. ( Kinda like a stealth sage mode

).
But somehow it feels to much of an asspull. Thou we shouldn't be talking like it's the last battle in Naruto so she could show where is she heading with her abilities.
There's also the possibility of her having a genjutsu, but genjutsu was featured mostly by Itachi's skill. And Itachi used it more for him to disengage targets than to fight them.