Summary
One Pieceis currently in the Final Saga and fans are thoroughly enjoying the ride as the story tackles its most intense elements. Given that the story is in the final phase right now, it is only a given that powerful characters are rising. Fans have already seen quite a lot of next-generation characters rise to the level of the likes of the Yonko.
Luffy himself is one such character who has recently become a Yonko. They are likely not going to be any more newly appointed Yonko inOne Piece, but there will be fighters who will reach this level. Among a plethora of fighters, only a handful can reach Yonko level in the Final Saga.

7Kozuki Momonosuke
Momonosuke is not a strong fighter right now and that much is clear to the fans. However, he has the potential to reach the same level as the Yonko and that goes without saying. Momo has the power of Kaido’s Devil Fruit, thanks to the artificial fruit that Vegapunk created. This gives him the exact same abilities as Kaido, the only difference being his dragon is pink in color.
Furthermore, Momo has the genes of Oden in him. He’s continuously growing stronger. Momo has vowed to one day surpass Oden and that time will come sooner rather than later. When it happens, Momo will have reached the same level as the Yonko. Perhaps, the fans will see this happenbefore the Final Saga concludes.

6Trafalgar Law
Law is one of the strongest Worst Generation pirates who, until recently, was in the running for theOne Piece.Law has a bounty of 3 billion berries on his head and he’s very close to the level of the Yonko already. Although he was destroyed by Blackbeard recently, Law can return stronger than ever before if he manages to regroup with his crew and set out on his journey once again.
Fans know him to possess tremendous powers and it is only a matter of time before he returns stronger than ever before. Law wants to find out the truth of the world and, for that reason, he has to reach a level of strength where he can hold his own and defend his crew as well.

5Yamato
Yamato is the child of Kaido and certainly an incredibly powerful fighter. She was born with the monstrous power of Kaido and her Haki is absolutely immense as well. She possesses control over all three Haki types and, at the same time, she commands the advanced version of Conqueror’s Haki.
On top of that, Yamato also has the Inu Inu no Mi, Model: Okuchi no Makami, which is an extremely overpowered Devil Fruit that grants her the ability to transform into a guardian deity fox and its hybrid at will. Yamato was already strong enough to fight against Kaido and hold her own in Wano and, with time, she’s likely to grow even stronger.

4Sabo
Sabo is an incredibly powerful fighterand the number 2 of Dragon.He’s already quite skilled and his infamy surpasses that of even Dragon already. Known as the Flame Emperor, Sabo has enough strength to fight against Admirals.
He still has a lot of potential to grow since he recently got access to the Mera Mera no Mi. Fans can fully expect him to get even stronger in the Final Saga and reach the same level as the Yonko. He is easily one of the most skilled fighters with a very high ceiling that he still has to reach.

3Sanji
Sanji is one of the Wings of the Pirate Kingand one of Luffy’s strongest underlings. He is incredibly powerful already, with a bounty of 1.032 billion berries on his head. Sanji has already grown into a phenomenal fighter, however, he still has a lot of room to grow. Oda has already told the fans to keep an eye on Sanji and his genetic development, suggesting there will be more that the story tackles in that regard.
Furthermore, as the Straw Hat Pirates keep on sailing the seas in the Final Saga, Sanji will encounter stronger foes, which will require him to get stronger as well. By the end of the series, Sanji will definitely have reached Yonko level.

2Roronoa Zoro
Zoro is the number two of the Straw Hat Piratesand certainly a powerful Yonko commander at the moment. He has reached an admirable level of strength, however, Zoro still aims higher.
He wants to become the World’s Strongest Swordsman and that means he has to defeat Mihawk. Fans know for a fact that Mihawk is a pirate whose strength can be considered to be on the same tier as the Yonko. Defeating him means that Zoro will himself be on the same level as these powerful pirates.

1Boa Hancock
Famed as the Pirate Empress,Hancock is one of the strongest fightersinOne Pieceand quite easily one of the most underrated ones. She has a bounty of 1.659 billion berries on her head, and her true strength is so great that even Blackbeard considers her to be strong enough to defeat him using her Devil Fruit.
Hancock also possesses all three Haki types and fans have not seen to what extent she can control them, however, given that the Kuja is a tribe based on Haki, one can expect her to be a complete master of the advanced forms of this skill. Hancock should not be written off and, in the future, she will prove herself to be a Yonko-tier fighter.