Given the general trajectory of most shonen anime, it's fairly clear that Monkey D. Luffy will be the strongest character in One Piece by the end of the series.
Against Shanks, even if Luffy possesses weaker Haki, the Devil Fruit abilities of the Hito Hito no Mi, Model: Nika can make up for the deficit and see him emerge victorious. Currently, however, Shanks is likely stronger than Luffy, simply due to the fact that the plot demands that of him.
In zoro vs luffy, luffy has greater will, greater haki and pretty much everything. Zoro loses easily.
While using Gear 5th, Luffy is able to extend his elasticity to inanimate objects. Luffy's devil fruit awakening allowed him to beat Kaido, who was considered the "Strongest Creature in the World." In his Gear 5th form, there are not many One Piece characters who can defeat him.
Shanks is probably way above Zoro`s level. Of all the characters still alive in One Piece, Dracule Mihawk is undoubtedly the strongest swordsman in the world. After all, he holds the title. Vista was the commander of the fifth division of Whitebeard`s Pirates and was considered the best swordsman in Whitebeard`s crew.
1 Shirahoshi
Her ability is known to be great enough to destroy the entire world and Luffy is her guide. Her existence alone can bring the entire world to heel and now that she has gained full control over her ability, it goes without saying that she is quite likely the greatest ally that Luffy has so far.
Magu Magu no Mi. Admiral Akainu's devil fruit Magu Magu no Mi is the ultimate weapon for absolute destruction. It is the most powerful raw power (even better than fire) in the One Piece world. This devil fruit allows the user to create and control magma at their will, along with turning themselves into magma.
It is a known fact that Kaido has lost to his fellow Yonko and the Navy a combined 7 times and been captured a total of 18 times. While Kaido might be the strongest in terms of raw strength, there are definitely those who can beat him a fight. Write for Us!
This allows him to eat 2 fruits.
Buggy is the captain of the Buggy Pirates and one of the Four Emperors of the Sea. A person who has not met Buggy can easily be fooled by his titles, but those who have know that he is one of the weakest characters in the series.
Dracule Mihawk, better known as Hawk Eyes, is recognized as the “World's Greatest Swordsman” in One Piece right now. Being the best swordsman of his generation, his swordsmanship skills are unmatched. Even Oda admitted that Mihawk's mastery over swords is far superior to his rival Shanks.
Mihawk is said to be close to the same level as Shanks and is even dubbed as the greatest swordsman, so to say Luffy would defeat Mihawk is still debatable in the eyes of many fans.
It is evident that the only person capable of surpassing Roger is Luffy. Even though Luffy still has a lot to achieve, he is the only person who can transform the entire world.
Oda added that such a battle could possibly result in the death of some characters. This ominous foreshadowing doesn't seem suitable for a fight between Red Hair Pirates and Strawhat Pirates. Given the connection between Shanks and Luffy, there's no hatred between the two crews.
Gear 10th Luffy is Luffy's ultimate form from the upcoming speculative fan-made sequel to One Piece, Son of the Pirate King. Luffy has continuously trained his haki and Devil Fruit powers during his time as Pirate King until he achieved this gear.
Over the years, he's faced adversity in many forms and overcome them with his many power-ups. Currently, Luffy is strong enough to fight the strongest of the Yonko in a one-on-one battle, making him extremely capable.
Goku is already a master of many abilities and operates at a much higher level than Luffy at his most powerful. While Luffy's Gear Fifth abilities are indeed impressive, they are not equal to Son Goku's mastery.