So, Demon Sheriff vs. King of Hell? Heavy Drinker vs. Zoro?
My view is
Luffy vs Teach obvious
Zoro vs Shiryu Swordsmen, first mates confirmed by Oda in Colorspread
Sanji vs Lafitte much foreshadowing
Usopp vs Van Augur Long range Snipers Marksmanship fight.
Franky vs San Juan Wolf. San Juan Wolf has a Df. Is called Battleship and Kaiju vs Mecha
Jinbe vs Vasco Shot. Water vs Alcohol. Might be Fishman. Looks like Blob fish.
Brook vs Doc q. Soul King vs Grim Reaper. Dead who appears alive vs Living who appears on verge of Death.
Chopper vs Jesus Burgess. Wrestlemania. Chrisas themed
Robin vs Avalo Pizzaro. History vs Nostalgia.
Nami vs Devon. Cat vs Dog. Trickster vs Trickster