 "Los Vatos Locos" immediately started a feud (storyline) with another AAA based stable known as "Los Vipers" and had many 4 on 4, or "Atómicos", tag matches.On February 14, 1999 Los Vatos Locos defeated the "Los Vipers" team of Histeria, Maniaco, Mosco de la Merced and Psicosis II to win the Mexican National Atómicos Championship.Their first run with the Atómicos title was short lived as they were defeated by Los Juniors (Blue Demon, Jr., La Parka, Jr., Máscara Sagrada, Jr. and Perro Aguayo, Jr.) only 63 days later.