Fierce One Piece battle between Roronoa Zoro and Warrior Braham from Shandian warriors that fought to take back Upper Yard from Enel. Braham's guns are not usual at all and they seem to irritate Zoro, but that of course is not a hindrance for him.
One Piece fight between Gan Fall and Priest Shura. Gan Fall was the former God of Skypiea, before Enel took over his place as a God. Even though that there isn't any of the Straw Hats participating in this battle it still is a high quality one.
Sir Crocodile was the very first of the seven Shichibukai (The seven Warlords of the Sea) who Luffy and the other Straw Hats met and actually had to fight against. He is a devil fruit user who ate the logia sand fruit and therefore can transform himself and everything he touches with his right hand into sand.
Very bloody battle between Roronoa Zoro and Mr.1 aka Daz Bones. Mr.1 (also called "Killer") was the strongest Officer Agent right after Sir Crocodile. Daz Bones can transform all parts of his body into steel thanks to the devil fruit he ate. This was the biggest challenge for Zoro (except Mihawk) until then.
One Piece battle in Alabasta between Sanji from the Straw Hats and Mr2 from Baroque Works. Bon Clay (Mr2) uses his devil fruit to turn his face into Nami so Sanji would not hit him and it all works well for him until Sanji finds out about his weak spot.