These are the attacks he uses with two swords. Nitoryu was also Zoro's original fighting style when he began to learn how to wield a sword, before accepting Kuina's sword and practicing Santoryu.
Taka Nami (鷹波,Taka Nami?, literally meaning "Hawk Wave"): While airborne, creates a powerful gust of wind to knock opponents over. It was first used to wipe out some Baroque Works agents at Whiskey Peak. It can be done while standing on the ground. Zoro says this attack is very useful against a group of weak enemies. The pun here is "Takanami" can mean "high waves" in Japanese. This attack was the first non-Santoryu technique Zoro uses in the series. This is called Hawk Wave in the Viz Manga and FUNimation dub.
Sai Kuru (犀回,Sai Kuru?, literally meaning "Rolling Rhino"): Zoro holds his swords in front of him pointing up, like rhinoceros horns, and spins quickly. This is called Rhino Cycle in the Viz Manga and FUNimation dub and Rhino Rampage in the English version of One Piece: Grand Battle! Rush! (dubbed by 4Kids). This was first seen being used against the Franky Family when they "ambushed" Zoro on the Going Merry. Pun with the Japanese pronunciation of the English word "cycle".
Nitoryu Iai: Rashomon (二刀流 ｢居合｣ 羅生門,Nitōryū Iai: Rashōmon?, literally meaning "Two Sword Style Draw and Resheath Technique: Castle Gate"): A dual sword drawing technique so powerful that it can split large obstacles in half. Zoro draws his swords, and sheathes them quickly, able to split two train carriages in half. Built in the year 789, the Rashomon, or Castle Gate was arguably the grandest and most famous gate in Kyoto. The name of this move probably comes from the double-gate/double-sword connotation, as well as being the 'grandest move' in his Nitoryu lineup. This was first seen being used to cut open two sea train carriages filled with Marines and World Government agents (none of the passengers were harmed at all). In the Viz Manga, this is called Two-Sword Style Castle Gate. In the FUNimation subs and FUNimation dub this is called Two-Sword Style Sword Draw Rashomon
Nanajuni Pound Ho (七十二煩悩（ポンド）鳳,Nanajūni Pondo Hō?, kanji meaning "Phoenix of the 72 Earthly Desires"; furigana meaning "72 Pound Phoenix/Cannon"): Same principle as the 36 Pound Cannon. Holding his two swords horizontally above the shoulder, Zoro then performs a circular swing that launches two air compressed projectiles spiraling towards the target instead of one, making it twice as powerful. This was first seen being used against Kaku to counter his "Rankyaku: Hakurai" technique. The attack's name is actually a very heavy pun, it's written out as "Phoenix of the 72 Earthly Desires" in the Manga with a skewed reading attached that makes it "72 Pound Ho" when read out. Ho means both Cannon and Phoenix, however the attached Kanji is for Phoenix, making that the literal translation and the "Cannon" reading a Pun on that, both of which are correct. The "Pound" part is a skewed reading of the Kanji "Bonnou" for Earthly Desires, and it is referring to the Caliber of a Cannon (a 72 Caliber Cannon would fire a 72 Pound Ball). This is called 72 Pound Phoenix in the Viz Manga, and 72 Caliber Phoenix in the FUNimation dub.
Nigiri (弐斬り,Nigiri?, literally meaning "Double Slash"): A stance where two swords are held parallel so that the tips are pointing to his right or left side, this move is like a pre-requirement to perform: Toro, Otoro, Hirameki, Samon, and Maguma. The pun in this is taken from sushi - the "Nigiri" in "Nigirizushi" roughly means 'hand-rolled'. This was first seen being used against Kaku. This is called Nigiri in the FUNimation dub.
Toro (登楼,Tōrō?, literally meaning "Climbing a Tower"): Two air-based projectile slashes are sent upwards while jumping as Zoro swings his swords in an upward motion. The pun in this is that "Toro" is an expensive cut of tuna for sushi; a more fatty cut than the normal. This was first seen being used against Kaku. In the Viz Manga, this is called Tower Climb, and in the FUNimation dub, this is called Tohroh.
Otoro (応登楼,Ōtōrō?, literally meaning "Reply Climbing a Tower"): Two air-based projectile slashes are sent downwards while falling as Zoro swings his swords downwards, with the gravity complimenting the force of the attack. The pun in this is that "Ootoro" is an even more expensive cut of tuna for sushi; the underbelly which is said to be the most flavorful flesh. This was first seen being used against Kaku. In the Viz Manga, this is called Tower Climb Return, and in the FUNimation dub, this is called Ohtohroh.
Hirameki (閃,Hirameki?, literally meaning "Flash"): Two air-based projectiles are sent forward after swinging both swords from the left or right side. The pun in this is that "Hirameki" is a type of sushi buffet. This was first seen being used against Kaku. In the Viz Manga, this is called Flash.
Samon (砂紋,Samon?, literally meaning "Sand Drawing"): Two air-based projectiles are sent diagonally down and to the left or right after swinging both swords from the left or right. The pun in this is obvious; it sounds like "Salmon", a common fish used for sushi. This was first seen being used against Kaku. In the Viz Manga, this is called Ripple.
Maguma (魔熊,Maguma?, literally meaning "Demon Bear"): A simple downward pound into the opponent with both swords. This was first seen being used against Ryuma. The name may be a pun on the Japanese pronunciation of "Magma". In the Viz Manga, this is called Demon Bear.
Dai Gekken (大撃剣,Dai Gekken?, literally meaning "Great Fencing Sword"): Zoro pierces two of his swords into Franky's heavy nunchaku and hits the opponent with it. This was first seen being used against Oars. In the Viz Manga, this is called Great Shock Slash.