I believe Blackbeard has the Whole Cake Island and Fishman Island Road Poneglyphs. Law said “You took the words right out of my mouth” when Blackbeard said he’d be taking Law’s Poneglyphs, indicating Blackbeard has some of his own. Blackbeard will beat Law and take the Zou and Wano Poneglyphs, meaning he’ll have all 4. Law will escape while Blackbeard returns to Hachinosu.
In a similar vein, I think Shanks has the Zou and Fishman Island Poneglyphs. He said that Kidd has the chance to give him his Road Poneglyphs and leave, indicating Shanks has some Road Poneglyphs but still needs some more. He’ll beat Kidd, get the Whole Cake Island and Wano Poneglyphs, and head to Laugh Tale while Kidd gets left behind on Elbaf.
Meanwhile, at the end of his Egghead Island escapades, Luffy will get the Fishman Island Poneglyph from Vegapunk, or from somewhere in the lab, since Vegapunk mentioned he was researching Poneglyphs. He’ll have all 4 Road Poneglyphs but will stop at Elbaf to drop off Vegapunk(s) and have a mini adventure. He’ll also meet up with Kidd, while Law escapes there after being beaten, and they all share information.
In Hachinosu, Garp fights through Blackbeard’s commanders and rescues Coby. However, Blackbeard himself returns and kills Garp using underhanded means, then leaves for Laugh Tale. This news reaches Morgans and Vivi, who manage to locate Luffy in Elbaf and give him the news. Wanting to both meet with Shanks and take down Blackbeard, Luffy heads to Laugh Tale.
Somewhere else in the world, Buggy finds out where Laugh Tale is. Don’t ask how, it’s Buggy. Unaware that others are also on their way, he goes to Laugh Tale to get the One Piece before everyone else.
Luffy, Blackbeard, and Buggy head to Laugh Tale, unaware that Shanks is already there, waiting for them. A clash between the Four Emperors is about to occur……
Meanwhile, Akainu crushes another cigar and rants about how he still can’t do anything. Poor guy should have just stayed a normal Admiral.
Theory by indonerd (https://www.reddit.com/user/indonerd)