It's the Fifth Grade MonstersFifth Grade Monsters series by Mel Gilden.
In the first volume, M Is for Monster (1987), Danny Keegan, a "normal" fifth grader, was introduced to the new kids in class. They include C. D. Bitesky (a vampire), Howie Wolfner (a werewolf), and Elisa and Frankie Stein (who bore more than a passing resemblance to Frankenstein and his bride). Gilden took Danny and the "monsters" through a series of adventures, most with plots that focused on the importance of young people's acceptance of kids who are slightly different.
