Princess Peach's castle has color issues that can't simply be fixed through lighting edits. It will require color nodes edits and maybe materials edits or something like that; for example, compare the background/castle colors in the video to this pic:
Not only color issues, but also problems with showing the depth of the objects, such as the mountain.
If I knew how to fix these kind of things, I would do it .-.
Also, the stage has other issues:
Stretched textures at the towers' walls in the back,
Missing object in the ceiling of the entrance,
Missing object between the main wall and the main roof,
Top tower's walls/pillars have too bright colors,
I dunno if the missing objects is the way the model is, but it can easily be fixed by putting pause-camera restrictions through STPM.
Is there absolutely no way to rip/copy the color nodes? Cuz that's really what we need to make it actually look like Melee.
Also, about Flatzone, would it be possible to apply the shine on the other textures on the Game & Watch? Such as the Smash Bros. texture, which doesn't match the surface itself.