I spent like 30 minutes just grinding Martha runs in an attempt to stumble over it already and I still have no idea how to trigger it... or what the best way to form power ups is. Or honestly what the best way to use Martha's is.
the best way to use an ability is to hit bosses until a bit of health remains. to perform it, you should have a full bar of gas and hold X/down button to kiss the boss... same thing with Sally and Bella