Technically, it's "Kamo-san Team". "Mallard" is just a disambiguating translation. The difference between "Team Duck" and "Team Mallard" in the original Japanese was that "Duck" ("Ahiru") referred to domestic ducks and "Mallard" ("Kamo") was a wild duck.
Also, the teams all have "-san" on their names, so it's actually more like "Ms. Hippo" and "Ms. Rabbit".