The fight is, undoubtedly, the most difficult one that Luffy has fought so far. Kaido managed to defeat Luffy three times. For the first time, Luffy faced defeat against him Kuri and was thrown in prison. There, he learned Internal Destruction Ryuo and took Kaido on during the Onigashima Raid.
However, physical blows without Haki don't work on him due to his rubber body, and the only slashing-style ninjutsu Sakura is shown to know is a scalpel-like blade. With that being her only weapon to hurt Luffy with, it's likely she will lose this fight in embarrassing fashion.
Quite easily one of the toughest battles that Zoro has been in is the one that he fought against Dracule Mihawk, the man who currently holds the title of the World's Strongest Swordsman. Zoro challenged him during the Baratie arc and found out the gulf of power between him and the World's Strongest Swordsman.
1 Luffy's Rival: Blackbeard
Blackbeard is Luffy's greatest rival and nemesis in the quest to find the One Piece.
Unfortunately, Luffy's rubber body doesn't make him impervious to fire, so Sasuke is already stronger thanks to his Amaterasu, and his Susanoo's arrows are strong enough to pierce Luffy's body.
Sadly enough, Zoro would have trouble fighting Naruto's most powerful Uchiha due to the Sharingan. Madara would avoid Zoro's attacks without even breaking a sweat, ending the fight only with a few hits.
Frieza is easily capable of defeating Baryon Mode Naruto in base form. Prior to the events of Dragon Ball, Frieza destroyed Planet Vegeta while in his base form. He did this without breaking a sweat or struggling in any way.
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.
Conis and the rest of Skypiea witnessed Luffy completely destabilize Enel's attack. She then witnessed Luffy finally defeat Enel by punching the god straight into the golden bell.
Deku is a very strong fighter but putting him up against Luffy is like putting a toddler against a WWE pro wrestler. HOWEVER, when deku unlocks all his Quirks and masters them, he could stand a chance against Luffy, but it would NOT be a fair fight, what so ever.
Tanjiro learned several techniques from his teacher and that allowed him to beat very strong enemies. But, Luffy is just a cut above anything Tanjiro has faced and it will be a one-sided match.
While Shanks' combat skills are seen very sparingly throughout One Piece, there's little to no doubt he's stronger than Luffy and could defeat the Supernova. As Luffy's role model, it wouldn't make sense to have him be stronger than Shanks at this point in the story.
Luffy is one of the strongest One Piece characters, but he likely can't defeat the entire Narutoverse by himself.
Luffy has the power of Gum-Gum fruit, making him a rubber man. He uses his ability quite creatively and has mastered all 3 forms of Haki. In a fight against Itachi, the current Luffy in his Gear Four is in a totally different class from Itachi. This Fight will be an easy win for Luffy.
Mortician: Sasuke was also way faster, Zoro was fast enough to keep with the teleporting Former King of Sorbet Bartholomew Kuma.
It depends on how quick the fight will last. Luffy's Gears are costly and can't be maintained for long stretches of time and neither can Baryon Mode for Naruto. Due to the number of drawbacks the Baryon Mode brings, Luffy will probably clinch victory in Naruto vs. Luffy if they break those modes out.
Saitama has superfast speed that allows him to cover long distances in the blink of an eye. When it comes to destructive power, Saitama can destroy giant spaceships, monsters, mountains, etc. with the bare minimum effort. Bearing in mind Saitama's feats, Luffy's Gear 5th stands absolutely zero chance against him.
In his base form, Naruto is immensely strong. However, when he combines his Six Paths Sage Mode and his Kurama Mode, he is stronger than anything Luffy will ever face. Even if Luffy were to get 10 more Gears, he still wouldn't be strong enough to stand up to Naruto in this mode.
Luffy has not surpassed Shanks just yet, otherwise, their future fight would hold no significant value. Luffy is close to Shanks in terms of power and it is only after their fight that he will officially be able to call himself stronger than Shanks.