After a year and a half, I have picked up Clickteam Fusion 2.5 Developer to make this little demo. Unfortunately, it won't work on Standard because it uses ListBox, but I have the exe (in the zip file) so you can play. The default controls are arrowkeys for player 1 and WSAD for player 2. Players 3 and 4 I don't know what it's set to.
You can add characters and assign a player controller for each as well as select and individually remove each character. This is to show how binding Platform Movement Objects and Active objects really works.
You might have issues with the arrowkeys suddenly changing the combobox inputs, but just click into the blank space of the ListBox and it will be unfocused which will let you play normally.
However, there are some issues: Sometimes when pressing many buttons, the PMO objects get a bit confused and so one instance using Player 1 doesn't jump synchronously along with another Player 1 instance. I'm not sure why, but I'd like you to check it out and tell me.