Is it possible to make good up/down moving platforms using the Platform Movement Object with 1.5? The character sits a couple pixels above the platform when it's going down, and is only stopped for a split second before falling through it when it's going up.
What you need to do here is have a floor marker and a different platform engine.
Don't give the platform a path movement whatever you do. Program it to move using events and Y co-ordinates, then when your character is on that platform (use the floor marker to detect that), move his in the same way too. I.e. when the platform is moving up (possibly use a flag or value to tell weather up or down), set platform Y position to platform Y position - 1, if floor marker is overlapping platform and platform is moving up, set player Y position to player Y position - 1. Then do the same for downwards but with + 1 instead.
This can be made more advanced by using Alterable Values to store the X or Y movement speed in pixels and to move the player according to the Alterable Values of the platform et cetera.