I'm about to talk about D-smash on platforms, here's a video demonstrating everything I'm saying.
While villager is on a platform above someone, D-Smash can still bury them on some stages. On battlefield, it works on Ganondorf and Rosalina while they are standing still. It's not as reliable against Bowser. It also works against some up tilts and up smashes, but it can still clank sometimes. Some characters get taller when they're doing the animation of almost falling off a platform. It works on dreamland against ganondorf, and on lylat, but on lylat it only works on the right side of the left platform, and the left side of the right platform, but this requires further testing. There's still a lot of testing to be done regarding this, but you can try it out yourself against any characters you run into a lot and are struggling against.