Not to be confused with Moonlight Sonata. Moonlight Serenade is an American swing ballad composed by Glenn Miller with subsequent lyrics by Mitchell Parish. In 1991, Miller's recording of Moonlight Serenade was inducted into the Grammy Hall of Fame.
Ice's weaknesses are negligible, for the most part, because you won't see much of the three types of Pokmon whose attacks are strong against them: Fighting, Fire, and Rock. Of those that are used, your Ice Pokmon should have little difficulty dealing with them.
The reason why ice is less dense than water is that the particular crystalline structure of ice has gaps in it on a microscopic scale. Water is one of the few (if not only) molecule that, in its solid state of matter, is actually less dense than it's liquid state.