Every 5 Years- Undertale AU Fanfic

Every 5 years a human is dropped into the Underground. Jason, Alex, Cheyanne, Dylan, Morgan, Keri, and Frisk are the kids that are dropped down, after Chara. It isn't just any human. It has to be a 5-year-old in highest of his/her class. These child geniuses have to fight in a sort of monster civil war. The Prophecies speak of the Three. These Three are the Torians, Undanians, and Gorians- but no other human knows. The Prophecies know that The Human has to pick from three; The Three. Who will win this war?