As we know Yonkos are ruling and fighting each other over the territory in new world. Ace novel explained how they never fight full all out war because even the winner of that clash would be in such a sorry state that he would easily be targeted and defeated by another remaining yonko.
Yet suddenly Big Mom said that if Lola accepted marriage she would be able to crush Kaido , Shanks and even Whitebeard and by now she would be pirate king.
So how suddenly she can defeat all 3 yonkos and become pirate king just by Lola accepting her marriage ???
Manga recently provided and answer for that question and that answer is Loki.
Here is what he said to Luffy .
He offered to destroy and I quote " one rival pirate crew of your choosing ".
Now Luffy is Yonko and his rivals are other 3 Yonkos . What this means is that Loki can destroy for example Blackbeard and his crew, or Shanks and his crew.
Clearly this aint bluff and Big Mom knew this very well, thats why she knew she could crush Kaido , Shanks and Whitebeard crews and become pirate king.
Yet suddenly Big Mom said that if Lola accepted marriage she would be able to crush Kaido , Shanks and even Whitebeard and by now she would be pirate king.

So how suddenly she can defeat all 3 yonkos and become pirate king just by Lola accepting her marriage ???
Manga recently provided and answer for that question and that answer is Loki.
Here is what he said to Luffy .

He offered to destroy and I quote " one rival pirate crew of your choosing ".
Now Luffy is Yonko and his rivals are other 3 Yonkos . What this means is that Loki can destroy for example Blackbeard and his crew, or Shanks and his crew.
Clearly this aint bluff and Big Mom knew this very well, thats why she knew she could crush Kaido , Shanks and Whitebeard crews and become pirate king.