I think that, in terms of "required elements", slapstick only really needs exaggeration and make-believe in order to qualify as slapstick. As far as physical and violent, verbal slapstick (such as the infamous quips of Groucho Marx) is very much a thing--though the argument can be made that verbal abuse is violent in and of itself. I feel that "ritualistic" is a misnomer here, and "formulaic" may be a better choice. But even so, that's not a required element in my opinion.
It's the exaggeration and make believe aspects that separate slapstick from outright violence and cruelty. The sound e