The marine have
Gorosei
Vegapunk
CP 0
Sengoku
Garp
Akainu
Kizaru
Greenbull
Fujitora
Gion (admiral candidate)
Tokikake (admiral candidate)
A lot of vice admiral
A lot of rear admiral
Etc...
Who can defeat this?? 8 admiral level..not includ 5 gorosei and CP 0
The marine can take yonkou and RA..the end
1.- Gorosei, CP's, Vegapunk dont fight.
2.- Sengoku and Garp are strong, they were at least Admiral Level in their prime. We dont know know if they are admiral level know, maybe they are Admiral level now since Aokji was stated the strongest of the Marines and then he was defeated by Akainu. So they might be in similar level since Garp also said he was gonna kill Akainu. Also, since they are old they wont be able to fight that much time and lose their stamina faster.
So we have 8 Admiral level Marines. I could see a Yonkou being able to fight them.
A Yonkou sick and old made Akainu lose conciseness for some seconds, that little time could mean death. So a Yonkou could at least fight two Admirals.
And then, the first 3 commander could give a fight to other 3 admirals. Maybe not win but also not lose with low or mid difficult.
We have 3 Admirals, well they would fight the others Commander gather up. It would be hard for sure but I think it is the Yonkou that could make the difference. I mean, the Captain is meant to be the strongest of all the crew and sometimes by much.
We saw how Big Mom could make a lot of destruction with Zeus and Prometheus, she could destroy an Island for sure with ease. And then we have that she destroyed the Elbafs with 6 years, I do think Admirals all together could defeat Big Mom with hard difficult, but 1 vs 1 I could see her with the edge, and if she fights them all 1 vs 1 she could almost defeat them all maybe.
A vice Admiral like Smoker was having hard time with Law, so a Vice Admiral could fight pirates of maybe 500 million berries. All the others are fodders.
But if we add the Warlords with that force then a Yonkou could lose.