The forces:
3 admirals, sengoku, garp, vice admirals, lots of marine fodder
Shichibukai
VS
Kaido, Whitebeard
King, queen, jack, Marco, vista,jozu
Whitebeard captains
Tobi roppo
Fodder kaido allies
Fodder whitebeard allies
Kaido has such a huge army. It changes the picture.
The admirals+garp+sengoku will extreme diff kaido and whitebeard.
I am skeptical if the 7 shichibukai can hold off 6 strongest yonko commmanders PLUS the other YCs I also think the yonko army and fodder are stronger on average than the marines. So the yonko commanders will run wild in my opinion and defeat the shichibukai IMO.
The marines have huge amounts of fodder which helps. Big numbers advantage for marines.
But wait... luffy and his allies can really change the tide of battle too. I dont see anyone stopping them from reaching ace.
I honestly think with kaido he extreme diffs the marines.
Winner: yonko and luffy extreme diff. Or a stalemate with extreme casualties on both sides.
No wonder shanks had to step in and save the marines from kaido