The children’s anime Soreike Anpanman is now the holder of Guinness World Record for the highest number of characters in an anime franchise.
Quoted from ANN:
As of March 27, 1,768 characters have appeared in the first 980 episodes of the Soreike! Anpanman superhero comedy and the first 20 Anpanman films. The producers actually submitted a world record application for over 2,000 characters in May, but some “characters” such as the Pan Kōjō (Bread Mill) and Baikin Shiro were disregarded by Guinness.