Olympus: Hades, now that they're following the Olympus attack plot he's gonna be the final bad. There could still be a coliseum set up in the world with other bosses, but I feel like maybe Hades with all 4 titans or a new Heartless/Nobody Titan would be the final boss.
Toy Box: Major Zurg vibes but it could be a ringer enemy. They talk all the time about Yozora and the game he's from maybe the "final boss" of that game will be the boss in this world.
Monstropolis: Randall seems more like a mid boss, but it could be a possessed Randall. I don't feel like the bosses are going to be just regular heartless or nobody bosses. They need to be more world related. Waternoose could have broken out of CDA custody? Or we could fight a manifestation of Boo's fears?
Kingdom of Corona: The twins and mother Gothel in a 3 way battle, maybe with the command of nobodies or as a mass of their power combined? I like the idea of her using Specter also.
Arendelle: half possessed Elsa would be pretty cool, wrest her from Larxene's grasp before she is too far gone. Hans was crafty and mostly non-conflicting, but he did pull out a sword at the end so a Clayton situation seems a lot more fitting for him.
The Caribbean: Davy Jones most likely, based on the movie's plot.
San Fransokyo: I also agree with some sort of Data Bug inside Dark Baymax being the final boss to free him from evil control. Either he could be given a new name and personality (Tron copy?) or they could copy Baymax's programming and have 2 Baymax.
100 Acre Wood: Woozles, since Heffalumps are friendly now.
Toy Box: Major Zurg vibes but it could be a ringer enemy. They talk all the time about Yozora and the game he's from maybe the "final boss" of that game will be the boss in this world.
Monstropolis: Randall seems more like a mid boss, but it could be a possessed Randall. I don't feel like the bosses are going to be just regular heartless or nobody bosses. They need to be more world related. Waternoose could have broken out of CDA custody? Or we could fight a manifestation of Boo's fears?
Kingdom of Corona: The twins and mother Gothel in a 3 way battle, maybe with the command of nobodies or as a mass of their power combined? I like the idea of her using Specter also.
Arendelle: half possessed Elsa would be pretty cool, wrest her from Larxene's grasp before she is too far gone. Hans was crafty and mostly non-conflicting, but he did pull out a sword at the end so a Clayton situation seems a lot more fitting for him.
The Caribbean: Davy Jones most likely, based on the movie's plot.
San Fransokyo: I also agree with some sort of Data Bug inside Dark Baymax being the final boss to free him from evil control. Either he could be given a new name and personality (Tron copy?) or they could copy Baymax's programming and have 2 Baymax.
100 Acre Wood: Woozles, since Heffalumps are friendly now.