I am going to theorize why does this theory makes sense. Please read it fully before giving criticism.
1. Luffy Preference.
First of all to join the straw-hats there are certain requirements. One of the most important of them is that Luffy needs to like what you are, this might sound silly at first but it's Oda's way of foreshadowing. We see example of this with Brook. Luffy wanted and desired a Musician so we have Brook.
In the same way Luffy absolutely adores Ninjas as we see when he first met Raizo.
Now you guys might be wondering what's that have to do anything with O-tama? Because O-tama has said it different times that she is going to become a bewitching shinobi(we will come back to this point in again continue reading).
2. Inherited Will
Now comes the second part. We know for a fact that Luffy carries Ace's will as shown in chapter 999 where he said he will come back to punch Kaido and we see Luffy fulfilling his promise in the next chapter. This inherited will dates back to marineford when Whitebeard said someone will come to inherit Ace's will.
Ace promised Otama that he's going to let her join his crew once she becomes a shinobi. Now you might think she's was just a child but promises are nothing to scoff at in one piece World. And through out wano we saw O-tama seeing Ace in Luffy. Luffy is going to fullfill Ace's promises as not doing so will stain Ace's Legacy and neither Luffy nor Oda will allow that.
3. Worthy of the Straw Hat.
Now comes one of the point which I personally considers a very important indication. If you are female and Luffy lets you wear the Straw-hat then you are going to join the crew. We saw it happens with both Nami and Robin. Now you might say Nami joined the crew before Luffy put the straw hat on her but that's wrong she never officially joined the crew until post Arlong park.
Now any of this to be true there is a simple problem, she's a kid. This is where Momo come in the equation. Momo needs to go back in time and master both his devil fruit and the way of sword and come join the second fight with the Yonko in the 4th act. Luffy and co are going to loose and the act 3 will end in tragedy. They are going to regroup again with bigger group.
Now why is it necessary for Momo to go back in time to begin with? Bonny can mature him but he's still going to be a child in his mind and weak as hell.
And with Momo having Kaido's duplicate devil fruit there needs to have a iconic fight between Kaido and him with both controlling the weather.
With how important Wano is with it's lore connected to both void century and poneglyphs Wano needs someone strong it needs a leader who atleast Admiral level. Momo is going to play a important part in the end of one piece.
Tama is going to go back with him train in seclusion and become a bewitching shinobi fullfiling her promise.
Also there's no way Toki is dead there's a reason she's from the void century she has further role to play in the story. Maybe sending someone back in time is the ultimate technique of her devil fruit and it will kill her.
"Conclusion"
Tama and momo are both going to go back in time and train in seclusion till the moment in present when they will be sent in the past(they can't change the history for present to occur that's why the seclusion) with Momo becoming the leader the scabbards need and Tama becoming the bewitching shinobi.
1. Luffy Preference.
First of all to join the straw-hats there are certain requirements. One of the most important of them is that Luffy needs to like what you are, this might sound silly at first but it's Oda's way of foreshadowing. We see example of this with Brook. Luffy wanted and desired a Musician so we have Brook.
In the same way Luffy absolutely adores Ninjas as we see when he first met Raizo.
Now you guys might be wondering what's that have to do anything with O-tama? Because O-tama has said it different times that she is going to become a bewitching shinobi(we will come back to this point in again continue reading).
2. Inherited Will
Now comes the second part. We know for a fact that Luffy carries Ace's will as shown in chapter 999 where he said he will come back to punch Kaido and we see Luffy fulfilling his promise in the next chapter. This inherited will dates back to marineford when Whitebeard said someone will come to inherit Ace's will.
Ace promised Otama that he's going to let her join his crew once she becomes a shinobi. Now you might think she's was just a child but promises are nothing to scoff at in one piece World. And through out wano we saw O-tama seeing Ace in Luffy. Luffy is going to fullfill Ace's promises as not doing so will stain Ace's Legacy and neither Luffy nor Oda will allow that.
3. Worthy of the Straw Hat.
Now comes one of the point which I personally considers a very important indication. If you are female and Luffy lets you wear the Straw-hat then you are going to join the crew. We saw it happens with both Nami and Robin. Now you might say Nami joined the crew before Luffy put the straw hat on her but that's wrong she never officially joined the crew until post Arlong park.
Now any of this to be true there is a simple problem, she's a kid. This is where Momo come in the equation. Momo needs to go back in time and master both his devil fruit and the way of sword and come join the second fight with the Yonko in the 4th act. Luffy and co are going to loose and the act 3 will end in tragedy. They are going to regroup again with bigger group.
Now why is it necessary for Momo to go back in time to begin with? Bonny can mature him but he's still going to be a child in his mind and weak as hell.
And with Momo having Kaido's duplicate devil fruit there needs to have a iconic fight between Kaido and him with both controlling the weather.
With how important Wano is with it's lore connected to both void century and poneglyphs Wano needs someone strong it needs a leader who atleast Admiral level. Momo is going to play a important part in the end of one piece.
Tama is going to go back with him train in seclusion and become a bewitching shinobi fullfiling her promise.
Also there's no way Toki is dead there's a reason she's from the void century she has further role to play in the story. Maybe sending someone back in time is the ultimate technique of her devil fruit and it will kill her.
"Conclusion"
Tama and momo are both going to go back in time and train in seclusion till the moment in present when they will be sent in the past(they can't change the history for present to occur that's why the seclusion) with Momo becoming the leader the scabbards need and Tama becoming the bewitching shinobi.
