how to make ledges like in any pokemon game
That is just an example, what will really help is the picture above it.
So like a one way platform,
You could just have a long object that is disabled until you pass it, then enable it to block the player.
You can also look at my semi-solid platform example:
https://flowlab.io/game/play/1060081
kinda like that but its top down and you cant go on it from the bottom