I'll continue to defend Delphino as an okay stage, but it's one we don't really need to use either.
Agree with ditching Duck Hunt. That stage is bad enough (but playable) in vanilla Smash 4, the heavy gravity only serves to make it so many characters can't reach the higher platforms without being wide open for a free punish. I'm a bit biased as Dedede player, but he barely gains any height off his jumps and his Up B has reduced height. I'll have to test if he can reach that lower tree platform, but if he can both of his landing options are way too laggy for him to effectively chase characters launched up there or those with good mobility that can actually reach the higher platforms.
I personally dislike Castle Siege as a stage, so I wouldn't mind seeing it gone, but it could use some testing to see how the heavy gravity interacts with the stage (specifically, transformation 2).
Wind on Dream Land is actually pretty hilarious for Dedede. When he swallows an opponent, they can wiggle around which disrupts Dedede's ability to move around and it kinda shifts him left and right...well, when he's on the edge of Dream Land and they're doing this, the wind will push Dedede off the stage and because he's so heavy he just instantly plummets to the blastzone.
This is just an imo thing but...whenever possible, I think we should use Miiverse over Battlefield. So that doesn't exactly work out online, but offline my reasoning is that Battlefield has really jank ledges, and the side of its wall is only actually a wall about halfway down the stage. So characters like Zelda and Mewtwo, their recoveries get redirected by a ceiling that doesn't actually appear to be there and they die because they couldn't ride up the wall. Other characters like Meta Knight can get trapped under this ceiling, which again it appears to be a wall but isn't.
At least on other stages where this could be an issue like Dream Land and Miiverse, the point where the stage is a ceiling and the part it becomes a wall is clearly defined.
As for the ledges, this is all vanilla but applies to SLHG as well:
I think the problems with the stage become more exaggerated when playing SLHG just because the ledge game becomes more important when recoveries are generally nerfed across the board. Speaking from personal experience, I've had far more problems with Battlefield in SLHG than I have in vanilla Smash 4. I wouldn't say it's a big enough problem to ditch the stage entirely, but I do think we should encourage use of Miiverse whenever possible...