Like Father, Like Son: He's every bit as gluttonous, hedonistic and hammy as his mother when no one's watching. Like Father, Unlike Son: His usual personality, as noted under Wacky Parent, Serious Child. What he actually is in private he is quite the opposite .
Katakuri also does not have that douchey arrogance that all of the other Big Mom Pirates exhibit because he actually is as good as he says and knows never to underestimate his opponents no matter what and admits his mistakes, which makes him a true through-and-through badass. He ultimately is this more than Like Father, Like Son above. Big Mom just considered her children tools to expand her power while Katakuri genuinely cared for his siblings to the point of brutalizing anyone who came after them . Logical Weakness: Katakuri's Devil Fruit substance revolves entirely around being sticky, so naturally, dousing him in water (or any kind of liquid) greatly nullifies its effectiveness. While Katakuri's Observation Haki lets him see farther into the future with greater accuracy than anyone else, it's still based on other people's actions and not his own. Once he does act on his visions and change the future he sees, it takes a moment for his visions to update in which he can't see anything, which is how Sanji is able to dodge his surprise attack. His immense Observation Haki requires an equally immense amount of concentration. Should something cause his concentration to falter, his Observation Haki is disabled until he regains his focus, making him a lot easier to hit.
It's also not something he can do every minute of every day; relaxing and recollecting himself is why he takes his private snack breaks. Luffy interrupting said snack time and catching Katakuri with his Haki down is how he discovers this weakness. Made of Iron: Good Grief is this man one of the tougher opponents Luffy has faced in a long while, practically on par with Lucci in tenacity of a fight. Sure Doflamingo took some doing too, but at least it took Luffy's Gear Fourth move to start breaking through his toughness and he managed to end the fight within two tries once he activated it. His combination of the Mochi-Mochi Devil Fruit and Armament Haki is so inhumanly tough that Luffy needs Gear Fourth to do lasting damage at all . Add to that an advanced Observation Haki where he can see every move coming and the extreme versatility of his Mochi powers, and you have quite the beast of an opponent. The fact that the fight took 10 hours is a testament of how strong Katakuri is. Marathon Boss: His fight with Luffy lasted almost as long as the latter's fight with Cracker did. For comparison, that fight lasted over eleven hours . Master of All: Even for New World standards, his versatility is extremely impressive, with raw speed and strength outclassing Luffy, proficient marksmanship, deadly spearmanship skills, powerful Armament Haki, an awakened Devil Fruit used with incredible creativity, and most dangerous of all, unparalleled mastery of Observation Haki that allows him to adapt and counter any situation before it even happens. The cherry on top is that he even has the frighteningly rare Conqueror's Haki . Memetic Badass: In-universe; Brûlée hailed him as the strongest Charlotte ever, that he has never laid down from the moment he was born, that he's always gallant, and never rests. All to setup the next chapter which reveals Katakuri's massive Hidden Depths . Their powers and techniques are very similar to one another, with their fight taking place in a literal mirror realm to drive the point home. Heck, they even look a little similar with their scars and untidy mop hairstyles. More Teeth than the Osmond Family: There is a giant, gaping maw lurking underneath that scarf of his and it is filled to the brim with pointy teeth. Fanservice: A handsome, hunky, and brooding Walking Shirtless Scene. My Greatest Failure: His inability to protect Brûlée when she was subjected to Revenge by Proxy by his childhood enemies haunted him into developing the fearsome, dreadful image he is today . My Kung-Fu Is Stronger Than Yours: Done to Luffy himself. Katakuri's Mochi-Mochi fruit allows him to stretch and contort his body just like Luffy, but it's superior in many ways; Luffy's body only takes on the properties of rubber while Katakuri can actually transform into mochi; Luffy's Gatling only creates the illusion of growing more arms while Katakuri can actually grow more arms; Luffy's Elephant Gun is limited by how much air he can blow into his hand while Katakuri's Elephant Gun can be any size he wants . Nerves of Steel: Not only does he largely maintain his composure when everything goes to shit during the wedding, but he stays completely calm even as the entire castle is falling over and taking him down with it. He even catches his sister Galette mid-free fall and dryly tells her to "calm down" as she (understandably) freaks out at their predicament. There's actually a good reasoning behind this; he has to stay calm and collected at all times in order to use his Observation Haki. While Katakuri was bullied and shunned for having a fanged mouth as a kid, he never cared much because he was strong enough to beat up anyone who laughed at him. It came back to bite him in the ass when his younger sister, Brûlée, was targeted and horribly scarred via Revenge by Proxy by the same bullies he beat up. Realizing that his carelessness got one of his siblings severely injured, Katakuri took extreme lengths to hide all of his "weaknesses", such as his mouth and eating habits, and eventually became The Dreaded so he could protect his siblings by reputation .
The real reason is more "Never let them get hurt again". Never Gets Fat: Like his mother, he is a glutton who eats sweets as often as she does. Despite this unhealthy habit, he still remains muscular and hunky. Nice Job Fixing It, Villain!: Despite being having almost perfect Combat Clairvoyance, Katakuri ends up making bad calls that fail to improve the situation for his family. First, he tries to snipe Sanji when he predicts that Pudding and the priest will fail to do so, only for Sanji to dodge and tip off the Vinsmokes that something's going on. Then, when Luffy and his clones appear to wreak havoc, he captures the real Luffy and tells everyone to ignore the transformed animals and focus on Luffy, which seemed like a good plan. except he made everyone ignore Brook (who disguised himself as Luffy), allowing him to sneak around and destroy Mother Carmel's portrait. Nigh Invulnerable: While he's not a Logia (anymore), his Devil Fruit gives his body blob-like properties as long as he's not wet, acting like one in spirit. He's been shown to shrug off getting shot, sliced, blown apart, and is even able to avoid Haki-infused strikes. This is actually an illusion he keeps up with his immense Observation Haki, morphing his body in tune with the enemy strikes he predicts so that it looks like he's unstoppable, but even being Made of Iron he will feel a solid hit just like anyone else.
The real challenge, as Luffy discovers, is overcoming that Observation Haki so he can actually get hits in. Nightmare Face: His Death Glare evolves into this when someone pushes one of his Berserk Button. He promptly slaughters the chefs who saw his face, and looked downright monstrous as he angrily confronted the childhood bullies who scarred Brûlée's face. On that note, his face itself, when revealed, is pretty darn terrifying, and quite vampiric, even!