Koopa Strength Itching Powder
From the Super Mario Wiki
Due to its name, it can be surmised that Koopa Strength Itching Powder was an invention of King Koopa and his Koopa Pack, to be used in battles. It can apparently be placed inside Bob-Ombs, which can, in turn, be carried by Albatosses and dropped on targets.
Once someone is doused in the powder, they steadily become more and more itchy, to the point that the itching becomes almost unbearable. No known cure for the powder was ever revealed, leaving how Mario, Luigi and Toad were cured of it unknown.