>>38389800A lot of Pokemon could frontline the series, but it was more about being appealing to both genders. I think Raichu does that, but not as well as Pikachu, especially thanks to the anime, he just sort of stuck with people, and the Raichu/Lt. Surge ep. was basically hard confirmation.
Just the same as Clefairy would have been an excellent choice, but it would alienate too many young boys/primary audience in most cases, Raichu is kind of the opposite of that, where it would alienate too many girls, which was still an audience, Pikachu didn't do this however.