"I'm WEAK!!!" The rookie said. "If i were to meet him now, it would be breaking the promise, right, Luffy?" the yonkou said, about he wanted the young one to return the memento once he became strong enough. I want to see when the young one done with his haki training, gear grading, and other skill upgrade to fulfill his promise to the original owner of the hat. No spectator, just the two of them trying to defeat each other and live to the fullest, without regret. Bittersweet and romantic, in a way.
Complete Luffy versus Shanks.
Let me see the other side of an ultimate legendary fight. We've known that there were two pirates who were equals with thick bond of friendship and rivalry between both of them. One was the strongest man in the world after Roger's death, and the other was the only one who (according to Akainu) defeated the strongest and became Pirate King. They were two men who created the great era of pirates. Opposing them were two strongest Marines whose abilities we've gotten a glimpse of, Sengoku and Garp. The Buddha and The Fist. But then, since the idea of pirate in One Piece is to represent "freedom", i must put the Pirates in a pinch. i'll put one more person in the Marine's, the "justice" enforcer's side, who is quite possibly even stronger than Sengoku or Garp.
The result is The Twilight of The Gods.
Gol D. Roger + Whitebeard, versus Sengoku + Monkey D. Garp + Kong !!!