I am still not able to wrap my head around to understand why oda made Buggy an emperor?
When they give someone a yonko title it strikes fear in peoples hearts, plus there are many pirates who try to align themselves to yonkos for protection.
This means the power of a yonko and its subordinate are sure to increase.
Now think it this way world government was trying to break avoid any alliance between the yonkos and they were worried when kaido and BM formed one.
Now they can't stop the news of their fall from spreading but if they made anyone from kidd or law a yonko who are still in alliance with luffy they would be facing a alliance of two yonko, plus if shanks join them world government will shit their pants.
Making buggy a yonko is a favourable option for WG as first he a clown and WG will be confident that they can control him, plus everyone knowing he was on rogers ship will make it more acceptable for everyone else around