This...is something that by all accounts should be simple to answer, but isn't, because of yet more DC Continuity Bullshit. Even so, I'll give it a try.
So. To start with, if you've ever seen the
picture of the now (defunct) DC Universe, it should seem pretty simple. Unless you start actually thinking about it, in which case it breaks down immediately. But we'll get to that later or maybe in another post; for the moment, let's consider. So on the inside, there's a bunch--fifty-two in that picture, more at other times--of different worlds that exist in the exact same space, but resonate at different dimensional frequencies. Around all those world in a metaphorical sense is the Speed Force Wall, also known as the speed of light, which is a limit to normal matter. Beyond that are a bunch of things that exist
beyond the Universe, such as the Sphere of the Gods, the Monitor Sphere, the Source Wall, etc.
Long story short, these places are outside the normal DC Universe and should be unaffected by what happens to it. The Reboots should not affect Hell or the New Gods or any of the Endless or what have you, according to that standard. And, in fact, there's stuff to support this!
...Occasionally.
You see, the Pre-Crisis Wonder Woman was given shelter in Olympus and survived until Infinite Crisis. During 52, the New Gods showed awareness of the different universes. And in what's perhaps the most critical, crucial, pants-darkening example of them all--Darkseid survived CoIE and lived through it.
I'll let that sink in.
Darkseid Is a Crisis Survivor, and so are most of the New Gods. The Darkseid that once went toe to toe with multiple Pre-Crisis Kryptonians, who caused the Anti-Monitors defeat, who treated worlds like dust in the air--that's the
current Darkseid still. He never died. He never changed. Nothing took his power. So he should be a tremendous, unspeakable threat, the Ultimate Tyrant, more than a match for Superboy Prime--a nightmare beyond imagining. Nothing like Darkseid has ever come among them: Nothing will again. Right!?
...
*cough*
Yeah, not so much. There's probably a bunch of things that play into it. One is just that, as you can probably guess, most writers aren't big on continuity. Given the choice, most will choose to play with interesting ideas, rather than check and see if they truly make sense--which isn't bad, in and of itself, but...well, it causes a lot of the issues we've covered and more. At the same time, Darkseid is a popular character with a lot of cool history behind him and people want to use him a lot...possibly too much, to the point that he shows up everywhere, but still. They want him to be the bad guy, to be fought, and to do that, we really can't have Pre-Crisis Darkseid around, or stuff like Legends would have ended really goddamn fast.
And I get that, really I do. I mean, sure, I know the history of Darkseid, the power he's sometimes shown, all of that--but do you think I'm going to bring in Pre-Crisis Darkseid here? Because I'm not, because if he did show up, the story would immediately end with 'And everything was horrible forever.' I don't really want to tell every story with the baggage that that guy
exists, either.
And writers have sometimes tried to explain it, generally in ways that don't really work--like him and High-Father holding each other in check somehow, except High-Father gets somehow taken out with regularity and Darkseid doesn't just destroy everything and which doesn't explain everything before CoIE, and such. But even taking that into account...a lot of stuff still doesn't make sense.
See, there should only be one Darkseid, Pre-Crisis or not. There may be 52 or Infinite Earths, but there's only one Apokalips. The different worlds are all the same to Darkseid!
Again, not so much. See, that's how it's supposed to be, based on that picture and the setting and the continuity--but stuff like that doesn't mean anything to the writers who want to play. So there's a Darkseid for New Earth and Prime Earth and those girl Darkseid's on Earths 9 and 11, Darkseid's on Earth 16 for Young Justice, on 17, 21, 22, 26, and 30, etc. There shouldn't be, logically speaking, but what does logic have to do with this? In the end, there
is. Just like how, in the end,
Darkseid Is but gets his ass kicked by what should, to him, basically be run of the mill punks all the time, like Superman a bunch or Doomsday that one time or whatever.
And in the same way that Darkseid should be beyond such things, but still gets rebooted whenever Earth does, the same is true of Hell. And as with Darkseid, it's not as impressive as you might think, most days. Like, you might think to yourselves, 'It's Hell!' You might think 'They're Fallen Angels and Demons, uncountable billions of years old, and wielding tremendous power!'
And then you might pick up a comic and go 'Oh.'
Now, some are! Don't get me wrong, some things fit the part, Lucifer especially. But you also have a whole bunch of people in hell who, uh, don't. You can read Hellblazer for plenty of that or just look at the many times the JLA or whoever fights Hell and wins, before/after Lucifer leaves. A lot of demons have a great deal of power, but if Lucifer's not on their side, the heroes of Earth might honestly be stronger than the entirety of Hell--and I only say might because of the occasional comic where the Demons Three switch people's bodies and some such. If you asked me how many times they'd laid siege to hell, I'd have to get back to you, because God knows at this point. Some have even done it
alone.
So long story short,
Darkseid Is! Except when he's not. And
All the powers of Hell! are usually about as effective as they were for Maleficent.