Poison Sting vs Onix is 1/4 effective. So, minumum damage before weaknesses or resistances is 2, halved and floored is 1, halved and floored is 0. What I'm saying is that according to the PS damage calculator, a move that is only 1/2 effective can cause 0 damage, even though 2 halved and floored is 1.In RBY it is very much possible that a move does 0 damage (i.e., "misses"), as the damage is actually floored prior to applying weakness or resistance, and the floor (2) only accounts for a single resistance. I even recall being personally very salty about this on original hardware, as I wanted to poison Brock's Onix to death but my poison stings kept missing >:(
A Crystal_ youtube video on the topic
That said, maybe somebody can point to a difference in link battle calculations (as opposed to in-game) that indeed floors damage properly.