He also wanted me to point out how Mario can also jump on the enemies and bosses which are consistently more deadly than the spin punch granted by Luma.
I'll start with this, I guess. The easy solution here is to list every boss and see how many can be harmed by both jumps and spins, just jumps, just spins, or neither, and go from there.
Also, yes, Mario can jump on most bosses just fine, but they don't react or take damage from it. I'm also not counting regular enemies, because they have no business scaling to 3-C in whichever category in the first place; If a goomba can tank a spin attack, we'd treat that as an outlier just as we would for that same goomba damaging Mario.
Though I could take the opposite approach and point out how many regular enemies can only be defeated with spins and not jumps, like Ruby Rocks or Giant Goombas :v
Dino Pirahna: Can only be defeated through spin attacking his tail, jumps don't work.
King Kaliente: Can only be defeated through using the spin attack to reflect his attacks back at him, jumps don't work.
Mandibug Stack: Can be defeated through ground pounds, not spin attacks.
Buggaboom: Can be defeated through ground pounds, not spin attacks.
Megaleg: Can only be harmed by redirecting its own attacks back into it.
Tarantox: Can't be harmed normally, only through using slingshots that can only be activated with the star pointer, which is heavily implied to be GML (though never explicitly confirmed).
Topmaniac: Can be jumped on, but this only causes his blades to retract. Spin attacking him is the only way to push him around and eventually damage him.
Bowser (SMG1): Can't be damaged with jumps or spins.
Bouldergeist: Can only be damaged by spin attacking bomb boos back into him, not with jumps.
Major Burrows: Ground pounds can force him above ground, but this doesn't damage him. Spin attacks are the only way to damage him.
Baron Brrr: Can only be extinguished with spin attacks, and can only be harmed with spin attacks afterwards.
Peewee Pirahna: Can only be defeated through spin attacks, not jumps.
King Lakitu: Can only be defeated by redirecting his attacks back at him with Yoshi.
Diggaleg: Can only be damaged by using the drill power-up to break the glass under his legs, which can't be damaged through any other method.
Gobblegut: Can only be damaged with spin attacks, not jumps.
Rollodillo: Can only be damaged through the Rock Mario power-up,
Bowser (SMG2): Can only be harmed by ground pounding the meteors he summons.
However, it's important to note that this fight is a massive scaling headache regardless of whether or not spins or jumps can harm him; This is someone who is comparable to Mario being massively amped by a Grand Star, and yet base Mario fights on par with him anyways
which is why Mario being amped makes way more ******* sense lol
Sorbetti: Can only be damaged with spin attacks, not jumps.
Glamdozer: Can only be damaged with ground pounds, not spins.
Squizzard: Can't be harmed with jumps or spins, only by shooting fireballs down his throat (which ig would be dura neg since you're attacking his insides?)
Prince Picante: Can't be harmed with jumps, only spin attacks that reflect his projectiles.
Boomsday Machine: Can't be harmed with jumps or spins, only ground pounds on the glass cockpit at the top, which like, no shit glass is more vulnerable than the rest of a giant mecha lol
Whomp King: Can only be harmed with ground pounds, though this isn't an example of regular jumps hurting 3-C amped beings, since this is the same guy Mario already fought in 64.
(didn't include the cannon bosses from SMG1 since they're fodder enemies in SMG2, or Mecha Bowser from that toy galaxy, since calling it an 'enemy' is a little generous)
Also not sure what to make of the bosses you beat with koopa shells (like Kamella and Kingfin), since you do the same basic spin attack motions to draw in and throw the shell, which could imply GML is amping the throw, but idk for sure. I'll just leave those out.
So you have 3 examples of jumps being more effective than spins (that aren't massive outliers, anyways), and
10 instances (11 if we're counting Tarantox, but that's whatever) of bosses that can't be harmed with jumps at all, ONLY spins (and a bunch of other bosses that defy both categories). The fact of the matter is, spin attacks being vastly above Mario's regular attacks outnumbers the opposite assertion by a factor of more than 3; At which point, the instances of jumps being above spins can safely be called outliers.
TL;DR: Spin attacks are consistently treated as the only way Mario can harm tougher enemies, which
is in fact evidence of spin attacks being above his regular AP. We have always given "higher with (x)" ratings or something similar to characters with techniques that can harm people their regular abilities couldn't touch,
so why is Mario the exception?
Mario also defeats bosses that terrorize multiple lumas regularly, so it wouldn't make sense for Mario to be leagues below a regular Luma naturally or for that one regular Luma to be above all those other Lumas. And Rosalina does the spin punch thing in Super Mario 3D World and has the same output as everyone else.
Per what Kirb already said, Lumas don't really fight, the energy they have stored within them isn't used for combat. It'd be like scaling a human to tier 7 because they can "overpower" a small chunk of uranium which could become a nuclear bomb; The potential energy is there, but it isn't really being used or anything.
As for Rosalina in 3D World, this is missing the point. Spin attacks aren't inherently big amps; Only the one granted by GML, since the whole point of this thread is GML boosting Mario's power to a level far above the norm. Since Rosa doesn't have GML in 3D World, she wouldn't really be on the receiving end of that amp.
Anyways, one last thing to note, GML does amp your stats in at least one way, that being speed. Spin attacks underwater make you swim faster, and spin attack ground pounds are notably faster than regular ones. Make of that what you will, but it does mean an amp is there to at least some extent.