all lps have sweepers some longer than others, brains have amazingly long ones three inches or so (remember this is different for every individual species, these are just generalizations), trumpet corals are relativley short mybe 1 1/2 inch or a little longer, frogspawn and other eupylia sweepers are about the length of their regular tentacles a little longer for clearing.
most softies battle by chemical warfare or over growing leathers are chemical warfare, mushrooms and zoas by over growing though I have seen palythoa Eat frogspawn tentacles. there is a lot of variety and no easy answer.