Sniffles was a mutant with incredible power. He couldn't give people colds, but he could stuff their nose instantly, forcing his opponents to breath out of their mouths.
In one fatal battle with Sabertooth, Sniffles unleashed the full extent of his power. While Sabertooth had him in a mortal bear hug, Sniffles raised his arm (which could bench an impressive 68 pounds) and placed it on Sabertooth's face -- causing his his nose to stuff and his ears to fill with wax. At first Sabertooth seemed unfazed, until the post-nasal drip forced him to gag and spit up snot.
While trying to run away, Sabertooth threw a car on Sniffles, killing him instantly. The funeral was attended by four people.