Buggy is the Moon God, Luffy's inverse.
Luffy heavily resists blunt attacks, but is weak to slashes, while Buggy is borderline immune to slashes/blades, but is weak to blunt attacks.
Buggy reflects Luffy: whenever Luffy does something, it ends up making Buggy stronger. Luffy beats Buggy, Buggy expands his crew, and nearly kills Luffy (Dragon intervenes). Luffy goes to Impel Down, frees Buggy and gives him an even bigger crew, then Warlord status. Luffy destroys the Warlord system in Dressrosa, and Buggy becomes a Yonko.
Luffy's feature is his hat, met to represent the sun rising on the horizon, the Dawn. Buggy's feature is his nose, which like the moon, is smaller than the sun.
Luffy does whatever he wants, Buggy's actions are always reflections of other people, like the Moon reflects light: Buggy will get strong now that Shanks is officially going to Laugh Tale.
Buggy will be big in Act 4, because Blackbeard (Davy clan), who is Moon associated, will be in Wano fighting against them with the Kozuki Clan, of the Half Moon Tribe (crescent moon).
"Those of the half-moon dreamed.
Those of the moon dreamed."
King, the Lunarian, will also be important, here.
Buggy is the "Star" Clown because he reflects the light of stars.
Like Luffy Awakened after dying in Act 3, Buggy will Awaken after sacrificing his life for Wano in Act 4, in Oden's honor.
Buggy will fight the God's Knights and Gorosei to protect Oden's Homeland