to not use a platform behavior: add a variable to the object called "drop"(or whatever) , and an always condition adding 0.09(or whatever you want the force of gravity to be) to "drop" than set y. position of the object to current y. + "drop"
if you don't mind having the platform object, and want its collision detection just set its max speed and everything else to 0, besides the falling.
--------------------------------------------------------------------------
fun with falling: if you make the falling your own event, you can have the object bounce by setting its "drop" to the current ("drop"/2)*-1 when it overlaps a solid object.