Yessir. In my not humble opinion, I've had many issues with this mon from the beginning. It seemingly is super powerful but it is so lackluster art doing its job as a breaker and/or sweeper most of the time unless you are running mono fat. Its attacks are not that strong either unless you're at +2 and even then it's meh and still frail at that. I think it's a child/newbie/callous trap because of how its seemingly sky-high attack stat. However, this attack stat by itself ignores 2 other main variables of the attack damage equation: move base power & ability.
For example here are some calcs:
+2 252+ Atk Life Orb Rillaboom Grassy Glide: 121.1 - 142.8%
+2 252 Atk Life Orb Kartana Leaf Blade: 143.9 - 169.5%)
+2 252+ Atk Life Orb Rillaboom Wood Hammer: 207 - 243.9%
+2 252+ Atk Life Orb Rillaboom Wood Hammer: 68.5 - 80.8%
+2 252 Atk Life Orb Kartana Sacred Sword: 63.5 - 74.9
252 Atk Life Orb Kartana Knock Off (97.5 BP: 103.8 - 122.8%
252 Atk Life Orb Dragapult Phantom Force: 105.8 - 125.8% ( worth noting that dragpault has almost half of the attack stat as kartana)
This is just a small anecdote but I show these to bring up some important distinctions, its relatively low base power moves and no boosting ability are lacking. This shows a small distinction ( I’m just using rilla and dragapult here as benchmarks, I’m aware there are others but the important thing is that many other mons hit higher attacking stats than this despite not having close to the same base attack because of abilities and movesets. And these mons are faster, a lot less frail than kartana, and have far better moves than it.
Is kartana weak? Yes if you are scarf but that is not what I am saying. Vs fat, which seems to be your (your being plural here not specifically you since you didnt mention this) kartana can do amazign things but so can other breakers. Kartana is pretty easily taken out specially , and faster mons do not need to be that strong or even unsually strong to kill it at all on the physical side :
+1 252 Atk Mew Close Combat vs. 0 HP / 0 Def Kartana: 260-306 (100.3 - 118.1%) -- guaranteed OHKO
+2 252+ Atk Life Orb Scizor U-turn vs. 0 HP / 0 Def Kartana: 259-305 (100 - 117.7%) -- guaranteed OHKO
252+ Atk Choice Band Barraskewda Close Combat vs. 0 HP / 0 Def Kartana: 328-388 (126.6 - 149.8%) -- guaranteed OHKO
252 Atk Landorus-Therian Earthquake vs. 0 HP / 0 Def Kartana: 141-166 (54.4 - 64%) -- guaranteed 2HKO
On the special side we know it dies, onto the next. Now you also asked especially C+. The mons in C+ are not bad whatsoever once you get over the rating of it even though this is all subjective. Kartana actually fits in very well with them, although I also think MANY of them are far too low in the first place.
Happy Tuesday
Kart can do it’s job regardless if the opponent has a Mandi or a Torn. Knock Off is so good for utility, but give it to a mon with 181 Atk and one that has most of it’s checks being mons that hate losing their items, and it’s OD. Even if Kart doesn’t outright break something in half it’s almost always going to force progress due to how busted Knock is. Even if it’s something as minuscule as taking away Tang’s Rocky Helmet, it allows you to pivot around Tang without worrying about chip damage. The reason why Kart’s mu vs Balance, Voltturn, and BO is so valuable is cause these three playstyle are the most common styles you’ll see on high ladder or tournament (More specifically tournament) and the fact that it’s a breaker that doesn’t mind coming in on non-BP Ferro, one of the most awkward mons to switch into safely, is also highly valuable. Also by calling Kart a noob trap, you indirectly just called great players who used Kart with success in tournaments like Leo, Luthier, and Storm Zone noobs.
Rillaboom hits harder than Kart but your forgetting some attributes that Kart has over Rilla.
-Kart takes less from rocks
-Kart outspeeds some of Rilla checks like Kyurem, Hydreigon, Zapdos, Offensive Tran, and Lele. Most of these mons are rising in usage due to the Ace/Mag ban. It’s helpful to know that Kart can murk three of these mons with Sacred Sword, and kill a crippled Zapdos with a LO boosted +2 Knock Off.
-Rillaboom hates losing it’s Band while Kart doesn’t mind losing LO too much which makes the mu vs Ferro much more in Kart’s favor.
For the calcs with +2 Leaf Blade vs Pult’s LO boosted Phantom Force, you used Mew. No shit Phantom Force is gonna look stronger. Test these calcs again but on Koko, and you get this.
252 Atk Life Orb Kartana Leaf Blade vs. 0 HP / 0 Def Tapu Koko: 282-333 (100.3 - 118.5%) -- guaranteed OHKO
252 Atk Life Orb Dragapult Phantom Force vs. 0 HP / 0 Def Tapu Koko: 208-246 (74 - 87.5%) -- guaranteed 2HKO
+2 252 Atk Life Orb Kartana Leaf Blade vs. 0 HP / 0 Def Tapu Koko: 563-663 (200.3 - 235.9%) -- guaranteed OHKO
Kart has less competition with the metas physical breakers due to how distinct it’s niche is compared to other breakers. Like there’s no way SD Chomp is gonna break past Slowbro without a lucky crit or chip.
Also no one argued that Kart’s physical bulk was fantastic, but for an offensive mon it’s really good to have, especially when you take into account it has the best defensive typing in the game. It’s not Slowbro levels of physically bulky, but it can take one or two strong physical attacks which like I said is great on a breaker. The calcs you brought out are mostly from mons that are either declining in usage, irrelevant in OU, or SD Lando.
DD Mew is outclassed by more consistent sweepers like Scale Shot Chomp and it’s better to utilize it’s ability to setup hazards than to attempt a budget Dragonite.
SpD Swords Dance Scizor is def a solid mon in the OU meta but Scizor LO SD Scizor is very rare and they don’t run U-Turn cause Superpower and Knock are much more valuable.
Barra has been declining in usage and viability cause everyone and their mother runs a good water resist and the fact that rain isn’t doing too well rn hurts it alot.
Who cares about being 2HKOd by offensive Lando when you threaten it out with LO Leaf Blade anywaya. Which let’s you force progress by simply clicking Knock as Lando is forced out.
252 Atk Life Orb Kartana Leaf Blade vs. 0 HP / 4 Def Landorus-Therian: 266-316 (83.3 - 99%) -- 75% chance to OHKO after Stealth Rock
Be honest. You may think Kart doesn’t deserve to rise to A tier and thats fine, but there’s no way you really think it’s worse than Buzzwole and on the same league as Toge.
The stuff regarding Mandi is valid but remember that Mandi absolutely hates losing Boots. Then consider the fact that Mandi has to check a whole bunch of other shit, most of which are common teammates of Kart like Lando, Pult, and Rilla which can just U-Turn on it then go into something that forces Mandi out. Then when Kart comes back and gets up a Swords Dance. This is what happens.
96 Atk Dragapult U-turn vs. 248 HP / 60+ Def Mandibuzz: 53-63 (12.5 - 14.8%) -- guaranteed 6HKO after Stealth Rock
+2 252 Atk Life Orb Kartana Sacred Sword vs. 248 HP / 60+ Def Mandibuzz: 269-317 (63.5 - 74.9%) -- guaranteed OHKO after Stealth Rock