Boyhood book series from the mid 1970s or earlier, group of chums at school (New England? boarding?), one of whom may have been named Moose. They excel academically, and participate in various sports, seemingly always coming up with an unlikely victory.
Gordon Korman’s MacDonald Hall series has a minor character named Moose, I think. The main characters are Boots and Bruno, two roommates who run into trouble all the time with their principal, Mr. Sturgeon, who they call The Fish.
There is also a Moos in The Mad Scientists’ Club books by Brimley, I think, but they’re not in boarding school. Just in a club.