AI tried to make an ombre rose cake and the icing wasn't stiff enough I guess cuz the bottom layer of roses is all squished. The top layer literally FELL off on one side. . .luckily it's for a friend who couldn't care less!! How can I fight gravity next time???

If it is too soft and not holding its shape you need to add more powdered sugar.  If they are falling off, you probably need to hold your tip closer to the cake so the icing is pressed a little into the crumbcoat.