@Kaido:
I'm not necessarily of the mindset that Katakuri's power variety is necessarily a bad thing. It's a good example of how versatile an experienced Devil Fruit user's skillset can be.
But everything else seems natural and creative.
I'm not against power variety. I love power variety. Crocodile even said in Alabasta that Devil Fruit users shouldn't get cocky and rely on one type of application of their abilities. So we should see characters relying on more than crutches of only one type of attack. My issue comes into play when the balance between them starts getting ridiculous and redundant, and don't really make much sense to me in how they can even be used in the first pace.
Luffy is a perfect example of a GREAT superpower. His body is made of rubber. That's it. It only specializes in being stretchy and inflated, unless blunt attack immunity counts too. But the ways that Luffy can use those properties for all sorts of attacks almost always makes sense. The only one that is an outlier is Red Hawk because of the random explosion/fire. His arms are stretchy, so he makes stretchy punches. His fingers are stretchy, so he can make stretchy nets. His stomach is rubber, so he can inhale air and inflate himself like a balloon. His bones and muscles are rubber, so he can bite into them and inflate air so that he creates strong giant attacks. His limbs can compress into each other in Gear Fourth because that is also what stretchiness allows.It all flows well in an intuitive fashion, with different levels of strength for each attack despite his moveset focusing exclusively on hand-to-hand based combat. The only part that gets annoying is how, post-timeskip, there's barely any difference in using a normal punch, an Armament punch, and a Gear Second punch due to Gear Second and Gear Third becoming parts of his natural moveset. So the Super Saiyan-esque power creep starts to seep in.
Haki is something natural that many people can learn, so Luffy is fine with using that. None of his forms of Haki, including Conquerer's, are uniquely special in any way out of randomness like Katakuri's five second foresight. The Voice of All Things doesn't tread over any abilities he can already do either. Your Katakuri analogy can't work specifically because he is not the protagonist. He's not even a main arc antagonist compared to Big Mom. So there's not much room to build suspension of disbelief around the versatility of his powers or explanations for them. Not that he can't have varied moves, but c'mon. If your first impression of Katakuri was seeing him do stretchy mochi kicks and somebody told you "hey, I bet he can exert pieces of his mochi body to form solid objects and weapons like jellybeans, earplugs, and tridents?", would you not find that the slightest bit farfetched? That it wouldn't be reaching towards something somewhat out of left field even if we haven't seen all of Katakuri's attacks? That is nowhere near as intuitive as believing that if Luffy can inflate his stomach, he can inflate his limbs like balloons by biting into them.
Big Mom bringing so many things to life makes complete sense though! Because it all operates on the simple intuitive premise that she can plant souls made from stolen lifespans into objects to give them life like Mickey Mouse bringing brooms to life in Fantasia's The Sorcerer's Apprentice segment. The only beings that stood out were Prometheus and Zeus since we have no idea where she would find a small sun or a cloud to put souls into. But as soon as we got explanations of Prometheus being a condensed inferno and forumers theorizing that Prometheus could have been made from a fog, then it makes complete sense. Although we still don't exactly know how exactly a bicorne hat becomes a sword, but I can let that go if only because of how fun and kooky it is and the shape being a clever parallel to rain guards of swords. Bringing a tidal wave to life is unexpected (and awesome), but makes complete sense (ignoring the debacle of sea salt weakness for Devil Fruits like with Moria's Devil Fruit). Big Mom has tremendous physical strength, but that does not overlap with how her Homies are elemental-based and differ in their range and applications. Even Napoleon as a sword isn't used as a normal sword but actually summons huge powerful gusts of wind that smash through things, so her powerful close combat's uniqueness and usefulness isn't redundantly treaded over again.
I find the five second foresight to be random and too unexplained to be believable, as well as unbalanced towards being OP or useless depending on Oda's writing. I find the object constructs from mochi to be random and a bit too distant from the premise of having a sticky/stretchy body. And the weapons feel redundant when Katakuri's mochi Armament limbs are doing just fine in varied close combat methods.
I like characters having contingencies and not relying on only one type of specialty. That's fine. I just want abilities to be varied on a FUNCTIONAL level as well as make intuitive sense with whatever concepts they are based around. I'm not saying that Katakuri has to only shoot jellybeans, or only stretch out mochi limbs, or only use weapon constructs. I am only saying that if his powers are going to expand out of those fields… have them make sense and cover different uses. Have them flow as a single, but layered fighting style of complementary abilities without feeling too cluttered. Because I don't get what a trident does that sticky extendable mochi legs coated with Armament Haki already don't do in precisely hitting your opponent at various ranges. And since when do you see somebody juggling between using a trident and trying to kick/punch somebody in the middle of a fight unless they get disarmed? It's weird, man.
I was actually fine with Doflamingo's strings at first. Before the Birdcage and Awakening, at least. He can manipulate people like puppets using strings exerted out of his fingers. That is an intuitive theme I can immediately understand, even if I don't know what they are made of. He can swing those strings as sharp attacks. That was unexpected, but cool, quirky, and still simple enough to grasp. He can shoot pieces of string out of his index finger like bullets. It doesn't go against how they are supposed to be sharp, he is only redirecting a string and maybe moving it faster but with less thread. It works as a unique and quick ranged attack. Overheat is a bunch of strings packed into each other that can slice through buildings with incendiary effects. The fire ability they have is random, but besides that, it works as a powerful attack because small thin objects like strings and sticks can become tighter and stronger when bound together. I could even only just BARELY buy into flying by attaching his strings to clouds because it resembled that of a puppet attached by strings to marionette control bars. It's cartoony enough to fit into One Piece.
His powers only got out of control once things like string clones and the Birdcage started happening. How can string clones be made, let alone talk? Why are several strings moving into each other without being attached to Doflamingo's fingertips for the Birdcage? What even is his Awakening and why did it need to exist other than revealing the concept of Awakening for Devil Fruits? It's stronger than his strings for some reason even though they can only be made of rocks or strings? If it's because they have Armament, he can just put that into his normal strings. What do they even really do that his string powers already can't do? Sure, they can puncture things, but his normal strings can already slice and be shot out as piercing bullets. How does a guy who controls strings even manipulate octopus-esque tentacles coming from the ground anyways? It looks dumb. He also blocked Luffy's Elephant Gun with a really thick spider-esque web, which I don't like because his strings shouldn't become that thick and it goes against what he tried to claim about Gear Second being too weak to affect him and Gear Third being too slow to hit him even though Luffy could have hit him with Gear Third that time.
In short, I don't mind power variety. Just the powers make intuitive and consistent in what they're themed around. By consistent, I don't mea stagnant. I love how Luffy's powers have progressed. As well as Brook's. Working in vague soul powers to give his sword attacks freezing effects from the cold winds of hell was great. Same goes for Robin learning to make clones of her self and giant limbs/wings made of smaller limbs that combine.
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