Okay this theory is based on all the events, plot threads and characters’ motivations that have occurred until this point that can be utilized to give a rough guess on how the Wano arc will occur. If these theories end up being right or wrong it’s only out of coincidence and inference from general story structure.
Alright, after the Whole Cake Island arc Luffy has probably accepted that going against any Yonko directly with minimal allies and no clear plan is just asking for defeat. So the early stages of Wano will consist of making a clear plan of attack and gathering a large force to challenge Kaido, while certain surprise assistance and problems will appear.
Early Plot-points that have a high likelihood of occurring:
1. A broken Marco and the remaining Whitebeard Pirates will agree to help Luffy, because he is Ace’s brother and will give him some information on the strongest members of the Beast Pirates.
2. During this time, Edward Weevil has followed the remaining Whitebeard Pirates to Wano. He’s planning on attacking them and is waiting for an opportunity.
3. The Alliance will meet up with others still loyal to the Kozuki Family and be revealed to other pirate allies who want to defeat Kaido.
4. The first group of pirate allies will be most likely the Kid Pirates with Killer in-charge and Hawkins Pirates with Basil present, who reveal that they will help if the Alliance promises to free Eustass Kid, which Luffy will agree to instantly.
5. The second group will be Gekko Moriah, Hogback and Absalom, who reveal that they have been in hiding since Marineford and have been keeping tabs on the Straw Hats since they returned. Luffy will try to fight Moriah, but Moriah will just asking tell him he wants to help Luffy, because he wants revenge on Kaido for what he did to his crew and the Alliance is the best chance to do it. Luffy will refuse at first, but then Moriah will beg him and ask if it were his crew, which would make Luffy agree.
6. The Alliance will get a rundown of the big players they will have to fight, which will include powerful members of the Beast Pirates, X Drake, Scratchmen Apoo, and those loyal to the Shogun, which will include Wano’s strongest swordsman.
7. The Alliance will formulate a plan, which will consist of multiple groups attacking certain points.
The groups will be split as following:
Group 1: Killer and Basil Hawkins (leaders), Nami, Robin, Franky, and Chopper, Absalom, the Hawkins and Kid Pirates, some Minks, some Wano allies. They will go free Eustass Kid and the other prisoners of Kaido, which will cause some of Kaido’s forces to try and stop them.
Group 2: Luffy and Law (leaders), Jinbe, Moriah, Usopp, Sanji, Bepo, Marco, some of the Whitebeard Pirates. They will attack the place where Kaido is.
Group 3: Kin’emon and Momonsuke (leaders), Zoro, Brook, Inuarashi, Nekomamushi, members of the Minks, Wano allies. They will face the Shogun of Wano
8. When the plan is made and preparations begin it will be revealed there is a spy among the group, who is feeding information to X Drake.
X Drake will not tell Kaido though, but instead use a hidden Den Den Mushi to contact Marine Headquarters and tell them to send Ryokugyu.
*Theory by Shiplord13