In the Zeekeeper’s fight with Dreamy Luigi Mario is able to noticeably amplify the power of Luigi’s attacks with his own strength. And this shouldn’t be an outlier, as Mario is also able to fight Antasma at his full strength (And while he’s helped/amped by Dreamy Luigi, Antasma separates Dreamy Luigi and seals him in an Antasmunchy at multiple points in the fight and Mario is still able to harm and take hits from him) who fought the Zeekeeper in the past, was stated to be able to consume entire Dream worlds and shattered the Nightmare Stone, the nightmare equivalent of the Dream Stone, was explicitly stated to be stronger than Dreambert, who also fought Antasma, fought Dreamy Bowser alongside Luigi, who absorbed the entirety of the Dream Stone, is comparable to Peach and Starlow, who could shatter the Dream Stone, Dreamy Luigi,
who’s stated to have a wavelength that allows him to become one with the Dream World, and himself can shatter chunks of the Nightmare Stone.
There are also several things/feats outside of Dream Team that would scale base Mario characters to Dream worlds, such as Mouser’s bombs (Which Mario and co. can tank)
being stated to be capable of destroying dreams in Super Mario Bros. 2 and the Star Spirits in Mario Party 5 stating that Bowser was going to
destroy the Dream worlds in the Dream Depot one by one
The Japanese version of Galaxy also implies that Mario universes are 5-D via containing 4 spatial dimensions, and there are several statements of the Mario universe and worlds compared to it in size being infinite/endless/bottomless, which would bump the Dream Depot to 2-A/Low 1-C and make several of the series’ MFTL+ feats actually infinite speed
I don't think there's a single thing you said here that isn't wrong or misconstrued in one way or another, so I guess I'll have to break this down because I'm a vitriolic fool who couldn't let a random VSBW post pass me by and had to waste a chunk of my night making a full reply:
1. Mario amplifying Dreamy Luigi's attack is just a bro move he can do to increase Luigi's spin torque during an attack, he's even completely visibly exhausted after doing it and iirc can't act again for a turn afterwards. Dreamy Luigi is pretty blatantly doing all the heavy lifting in every Giant Dream Battle. They're all Luigi's big moments to shine with Mario just kind of assisting wherever he can. It's also worth noting that M&L don't even really "defeat" him, the fight stops and the Zeekeeper commends them for fighting well, he's clearly not super beat up or even looking to be all that effected by the end of the fight. He also isn't even at full power in this fight. He was literally just awoken from a long, long slumber (I honestly forget how long the events between DT and the Pi'illo lore takes place ngl), states that he's "tired and old" after the fight ends, and visibly even remarks he's out of shape and weaker than he used to be when ONE usage of the Wakebeam completely tires him out and forces him to rest again. AGAIN, that Wakebeam that completely drained him was just to destroy a BARRIER created by the Dream Stone in the first place, not even the full might of the Stone in the first place. Base Mario does not scale to Zeekeeper at his full might when he fought against a Dark Stone empowered Antasma, and logistically doesn't even scale against the weakened Zeekeeper that appears in Dream Team.
2. In the past when Zeekeeper and Antasma fought fought, it was when Antasma had the Dark Stone, which would have empowered Antasma far more than he was during either of his fights with Mario in Dream Team, considering that the Dark Stone is supposedly a full counter in power to the Dream Stone. Mario cannot be scaled to Antasma with the Dark Stone since he obviously never fought him with it, and Antasma's full power without the Stone is completely unquantified and unknown. The best we can do is upscale him from Base Mario, since Base Mario obviously never stands a chance against him in the fight, and is even stomped by Antasma in their first encounter.
3. Mario needs the full amp of Dreamy Luigi and assistance from Dreambert in his battle with full power Antasma in the Dream World to defeat him. In fact the very example you give of Dreamy Luigi getting pulled out of Mario to lose his amp showcases the huge difference in power between Base Mario & Antasma, Base Mario's AP and Defense are severely weakened, his attacks to pitiful damage to Antasma, and the damage he takes from attacks without his amp are extremely high, he couldn't reasonably take more than a few hits without dying. If anything this showcases that Mario shouldn't be comparable to full power Antasma, since the fight goes out of its way to show how Mario is out of his depth without Dreamy Luigi & Dreambert's assistance. At best its an outlier.
4. Zeekeeper fought with a Dark Stone empowered Antasma in the past, incomparable to the Antasma we see in Dream Team itself.
5. Shattering the Dark Stone or Dream Stone likely doesn't give you AP comparable to the power they channel. They're just stones, and they're not really showcased to be anymore durable than a regular stone. Starlow has never been showcased to be a powerful entity within the series, and from memory usually gets slapped the **** around if anything. Her destroying the Dream Stone, if the stone really was as durable as the entire Dream World combined, would be more of an anti-feat for the Dream Stone if anything. There's plenty of artifacts in fictional verses that work like this, I don't think we grant them special durability unless they actually have feats of durability themselves, like surviving specific attacks or being stated to withstand an attack. Most fictional power sources get a "Unknown on its own, grants [insert level of power] to its wielder" when it comes to stats. The Dream & Dark Stone would be no different, considering both have showcased pitiful durability, since one got shattered by being crushed in someone's hand, and the other got decimated by a fodder's laser beam.
6. Dreambert's power is pretty unquantified within Dream Team as well. The only feats we really have for him are him being involved in defeating Antasma in the past (and iirc, Dreambert wasn't even able to defeat him then, they literally couldn't defeat Antasma so they had to seal him away instead), him jobbing to Antasma within a few seconds in the future, and him assisting Mario by amping/healing him in Mario's fight against Antasma. He's not really useful in any scaling here.
7. I'm 100% sure that the Mario & Luigi vs Dreamy Bowser fight is considered the biggest outlier/anti-feat in the series. Mario & Luigi were unable to break a BARRIER made by the Dream Stone not even 30 minutes earlier, to the point that they had to awaken an ancient deity to use his (current) full power to use his strongest attack to shatter said barrier. But then, just 30 minutes after this, they fight against Dreamy Bowser, who absorbed all the fragments of the Dream Stone and thus pulls upon its full might. Despite Mario on his own not being able to match Antasma's full power, despite Mario & Luigi COMBINED not even being able to destroy a BARRIER made by the Dream Stone earlier, they are suddenly able to match, and then surpass the full might of the Dream Stone, knock the power out of Bowser, and then send him packing, all in one go. It's a blatant, unavoidable outlier or anti-feat. Either this is PIS, Mario & Luigi are operating at a level they've never operated at before and never will again, or its an anti-feat to Dreamy Bowser / the Dream Stone and implies they're not actually as strong as they appear. Nothing about this feat makes sense or can be applied logically within the verse.
If this feat was allowed, we could get 2C/2B Base form Classic Sonic by fighting the Phantom Egg, which was powered by the Phantom Ruby.
Take it at face value, well, that means Mario & Luigi are multiversal, oh, but also Bowser, because he physically scales above them, but wait, if he scales above them for being stronger than himself but amped, why did he even need the amp in the first place? This also means that various characters that upscale/downscale from Mario are also now Multiversal via an arbitrary circular scaling chain. Does anybody like Multiversal
Phantamanta? Well that's what this feat would create. It's asinine and its why its discarded in basically every versus circle ever.
8. Universal+ Mouser is perhaps the funniest ******* thing I've ever run across on this site. I guess it's technically not wrong? It only really applies via cramming how dreams operate in Dream Team (a game made in 2013) to a brief sentence in Mario 2's manual from the 80s but whatevs. I still have problems with this. For one, the bombs don't visibly destroy the dreams your in, if they really did destroy dreams, shouldn't a bomb going off just nuke the entire stage? I guess you could make an argument of the colorful flashing in the background being "the dream shaking", if you really wanted to stretch this to a ridiculous degree. Wouldn't this count for some kind of haxx anyways, since they don't just indiscriminately destroy dreams, only good ones?
I'd say the most damning thing for this "feat" would be the fact that:
Everything that occurs in Mario 2 is just a dream. Not the type of dream you jump into like in Dream Team and interact with physically via Luigi's dreams opening a portal, no, it's literally just Mario's dream while he's asleep. Nothing in this game can be used for feats for the mainline Mario cast, since nothing that occurs in it actually happens or scales, lol.
9. Can this Mario Party 5 feat even be used? Bowser never actually destroys any dreams in the first place. It's not specified HOW Bowser is going to destroy the dreams either. Is he going to physically crush them? Is he going to use a machine? Is he going to use another esoteric power source to do so? There's nothing to USE here, it's just an empty threat with no feat or example to really back it up.
10. Okay this is getting ridiculous. Please, PLEASE give me the evidence for 5D Mario universes and Infinite Size shit. I've never once heard this at any point in my life and people regularly scrub the Japanese translations for Mario games since a lot of the English texts have notoriously lacked context for higher tier feats in the past, such as the English version of SM64 saying that Bowser "created" the Painting Worlds with the Power Stars, when in the Japanese version he did no such thing.
I have yet to see anything solid for Base Mario or Luigi scaling to anything Uni, especially Dream Uni stuff.
I don't think mainline Mario surpasses Galaxy level via Luma Amping honestly, there isn't really anything that's not massively questionable to scale to.
