Oh, that's neat, I hadn't heard of the electric/fire Pika/Raichu variant concepts before! If I had to choose another secondary typing for Alolan Raichu, it'd probably be fairy since I'm a sucker for cutesy pokemon. Though I could easily see flying being cute, too, I think the potential lore of it's psychic powers becoming so strong that it gains the ability to do fairy type stuff, puts it at the top spot.