So after this spoiler, we know that:
Kaido&Big Mom and folder Shougun are ready and have the advantage cuz they got more Intel - they have 40k folder + 10 veterans - 4 commander - and some low-veterans level - question mark the number (stronger than veteran?)
Straw-hat, Law crew, (Kid crew?), x-drake (?), Hawkins(?), 9 scabans, o-tama (with her axe devil fruits), minks.
Big question mark about the rox legend?
During act 2 we have learned 2 ways to arm Kaido:
Luffy advance armament hacky (we dont know how good is luffy with this new form - he had 7 days to master this form)
Zoro using Ema (we dont know how good zoro has learn to control this new sword - Zoro got this sword when he had 5 day left for the festival)
Who could potentially fight kaido?
Luffy (100% from the start )
Zoro (100% not sure when he ll take part)
Kid (90%) - Kid ll have a part but what exactly? He has failed the first time - does he get a power up? Will he be just a punching guy?
Law (20% - what could potentially do law to kaido? ) / - I see law against a commander
9 scabans (80%) I believe they ll intervene a few times against kaido - not major role though
Big Mom (50%) - change side for some unknown reason
Big Mom
No idea who ll face Big Mom (luffy? I dont think so)
Any of the worst gen? I dont think so
The rox leged? maybe
marines? (I dont think so, there are already to many groups)
black bear pirate? (maybe)