I've noticed that stuff like season numbers and similar have been added to character pages once or twice. Please don't do this, as it makes it really hard for people using the wiki as a resource for episode numbers to find the episode they were looking for under a pile of characters and character names.
This also is something that should be noted the other way around : adding character sorters to episodes (with the possible exception of /maybe/ 'Magical Beings', and even then it'd be better to set up a 'Episodes that feature magical beings' category) makes it hard for people to find stuff, because if you tagged every ep that featured a given gender, it would become nearly impossible to find characters in the 'Males' or 'Females' sections of pages.
On that same note, the 'Opening Themes' category is for just that, opening themes. I don't think you're supposed to put characters that just so happen to sing or feature in the opening themes in said category, because, again, it makes things cluttered and hard to find.
Please think carefully before you add over 15 new categories to a character page, it might just be making more work for other editors and browsers of the wiki.