Okay, to start this blog, I'd like to say that this isn't anything necessarily new that the information here presented will be from, just new realisations that have come from the information we've had. Some of it was overlooked, and some of it I've merely recently discovered. I will say that it's a shame that the absurdly high-end 2-B Dream Depot status and thus the absurdly high-end 2-B feats and the absurdly high-end MFTL+ Bowser will no longer exist after this blog, but I'm glad to say that our new realisations have definitely made up for it. Dreamy Bowser and those who scale to him will still be 2-B, however, so that still exists.
What We Already Should Know
Okay, for anyone new to the concept of the Dream Depot in the Marioverse, I'll just review the premise of what it entails, the basics of it. This is the Mario Party 5 manual, which I'll be referring to throughout the explanation of the Dream Depot. On page six, they refer to the Dream Depot as a "real world of dreams" and also note that it collects everyone's dreams. These statements imply that everytime someone dreams, a real dream is created within the Dream Depot. How big are these dream worlds? Well, Dreambert refers to them as "dream worlds" and "world", the way he uses it, refers to the universe. Considering that constellations exist within these dream worlds, and other showings of space exist in these dream worlds, so that combined with the comparison to the real world should be enough to say that they're universe-sized. If that's not enough, then Misstar calling them universes, along with what page 28 of the earlier cited manual says about the dream worlds definitely confirms that they're real universes made.
Tl;dr, everytime someone dreams in the Marioverse, a real universe is created.
The New Stuff
Throw away most of what you know about how big the Dream Depot is. That's literally less than trash compared to the new Dream Depot. So colour is what gives everything it's life, essence, and the Black Paint is fully sentient. This means that everything in the verse, all things with colour, are sentient. Every drop of colour is sentient. So, in the Marioverse, there are worlds with infinite size. The Super Mario Brothers 3 guidebook says that the pits in Bowser's Castle are bottomless. Before this is passed off as hyperbole, the guidebook also clarifies that World 8 is the Underworld, so it makes perfect sense for them to have literally bottomless pits, and thus, be infinite in size. Evidenced by statements earlier in the guidebook, each level is a separate world, and they clarify when worlds are smaller, calling then "mini-worlds", so every level that isn't a "mini-world" is a world of infinite size. To address any point that "you can walk between worlds, so they can't be infinite", in that last picture, it says the hands "take you to the mini-worlds", so it's evident that you go through some sort of portal or rift when going to the different worlds. Because worlds exist that are infinite in size, they must have infinite colour, and thus, infinite sentient beings. It's also directly demonstrated that beings of just paint can also sleep.
"B-but wait, Hadou. What if only blackness is sentient? And underworld fucking schmunderworld, that must be hyperbole!"
Well, this is my opinion, to start, but if only blackness was sentient, that would ignore the things in the world that aren't black, yet sentient. And the underworld having literal bottomlessness is a common trope in fiction, so I don't understand what's wrong there. Infinite sentient beings = infinite universes. That's pretty simple. You would think that it would end there, but everytime a universe is made, there will be people dreaming in there.
"N-no, it doesn't work like that!"
Sure it does. There are beings within the dream worlds, I mean, anyone who has played Super Mario Brothers 2 knows that. It's also evidenced that people can dream within dream worlds. So yes. It does work like that. Now, from here, it's simple logic.
Let's just say we start with a single universe of infinite size. In actuality, we start with more, some infinite, some not, but for the sake of simplicity, we start with one, of infinite size.
On the first night, there will be infinite dreams, and thus, we will have infinite universes. This is the equivalent to a multiverse with infinite space-time continuums, or infinite 4D.
On the second night, every universe will spawn infinite universes, and thus, it gets infinitely larger than it was before. Infinite sets of infinity, uncountable infinity. This is the equivalent, persay, to a 5D universe.
On the third night, of the infinite sets of infinite universes, or the uncountably infinite universes, there will be infinite from every universe spawning again, and thus, what was equivalent to a 5D multiverse is now getting infinitely larger; the equivalent to infinite 5D universes.
On the fourth night, the infinite sets of infinite sets of infinite universes, or the uncountably uncountable number of infinite infinities will now each spawn infinite universes. What was the equivalent to infinite 5D universes is now uncountably infinite 5D universes, or 6D.
Following this valid pattern, we know that the size of the Dream Depot should be following a certain formula. Since the Star Spirits have been watching over Star Haven since the beginning of time, it makes sense that they've been watching over the Dream Depot just as long. So the formula for dimensionality is...
We start with four dimensions, and every two nights, what's contained within the Dream Depot raises a dimensional level. This is a fair formula, right?
Okay. Well, here's the thing.
"Here, in this place, your sins from your time among the living are weighed. If your sins are light enough, the bliss of The Overthere will be yours. But if not... You suffer for eternity among the game-overed! Now let us weigh your sins..." - Jaydes
These three statements from Jaydes, the Queen of the Underwhere who is undoubtedly one of the most immortal characters in the verse, has statements with certainty that time will go on in the verse for eternity. So what can the Dream Depot contain? Well, the "x" in the formula is the number of nights. Time will continue for eternity, so the Dream Depot must be able to contain infinite nights' worth of dream worlds. (∞/2)+4.
Well, the answer to that is simply infinity. The Dream Depot is large enough to contain many infinite-dimensional worlds.
I can even go further onto point out that Rosalina said that the universe resets itself throughout a cycle of rebirth. Since eternity exists and time is reset, we can interpret this to mean that an infinite number of time passes between the universe's cycle of rebirth, and thus the Dream Depot can contain enough to let endless eternities pass.
This makes the low-end being several infinite-dimensional worlds and the high-end being several infinite^infinite-dimensional worlds. This is a valid high-end, not a remotely exaggerated one. Even if you strongly deny this for some reason, the Dream Depot still definitely contains and encompasses an uncountably infinite number of dreams, and then likely contains and encompasses many infinite-dimensional worlds, so I would rate those who scale to the Dream Depot feats High 1-B.
Tl;dr, the Dream Depot is definitely at least infinite-dimensional, likely repeating an infinite sets of infinite nights onto that.
I'd like to thank my friend Metal for providing some of the links I've used here and for some of the old explanations of the Dream Depot.