its different in different fighters
in 3-d fighters like tekken/soul cal, "crushing blows or overheads" will hit someone ducking, since most highs will generally wiff a crouched opponent, its just easier to call em mids usually
low attacks need to be blocked low
in 2d and 2.5d games (street fighter/blazblue) u wont hear the term crushing so much, and "highs and overheads" mean you need to stand up to block
low attacks must be blocked low
You wont hear the term mid attacks so much as moves are generally classified as high or low. If they're not one or the other, they can be blocked in either state so it doesn't really matter.
