These enemies drop freezing bullets when they get into range. The bullets are very weak, and barely freeze characters when they get struck regardless. In the stage, they're barely a threat, and can even be frozen. They also drop 3333 Gold, making them useful for grinding money.
In the boss screen, they have an tendency to bait characters into attacking them and not the Brown Boss Box Germ in the area, which is by far the bigger threat. Since they have decently high LP, an optimal way to get rid of them is to pound them with powerful attacks to remove them as soon as possible.