Let me just do math to explain how many worlds we're dealing with that Count Bleck can destroy.
Let's say one day a billion people dream. Obvious low-ball, but still.
Now, there are a billion people in those billion dreams. So now there are over quintillion people dreaming the next night.
And then we're dealing with quintillion dreams each holding a billion people. So then we have nonillion people.
The next night, nonillion dreams with a billion people. So now we have dodecillion people.
And the next night, dodecillion dreams. I don't even remember the number that we're dealing with at this point, and we haven't even reached a week, yet. Following this pattern, though, within a week, we have univigintillion dreams or something like that. How about a month? Or a year? Or centuries, or eons, or since the birth of the universe? I mean, and then alternate timelines stem from them, because we know Bowser changes history in Mario's Time Machine, and then we have the time traveling antics in Partners in Time, and the time traveling antics in Super Paper Mario and so the dreams of the people in alternate timelines are taken into account.
And like I said before, billion is certainly a low-ball. As we know from various Mario games, more things are sentient than even make sense to be sentient. Earth as we know it exists in Mario, so that's already over a hundred billion people that have ever lived. And then the anatomy of Koopa, similarly to as we know inside of Bowser, all of his memories, every unit of knowledge, every blood cell, they're all sentient. All of these things would essentially be dreaming. And all of these dreams become real.
Like I said, the statements from Trunks in the manga have been retconned, and this is because in Super, there were only six or seven timelines, and we know that because of the Time Rings. Alternate possibilities Ôëá alternate timelines, or else they would be 2-A because statements regarding infinite possibilities. Demigra is 2-B based off of there being tons of worlds with 12 universes and myriads of alternate timelines, and does not equate to anything on the level of the hundreds of millions of universes with countless other worlds each with tons of timelines each with tens or hundreds of more worlds that we know of in Pokémon, or the exponentially increasing number of universes with alternate timelines that we know of in the Marioverse.