World Championship Wrestling (1998)
In World Championship Wrestling, Chavo and Eddie were not really a tag team as they were later on in WWE. Chavo had only a year of experience in contrast to Eddie's eight or nine years. As part of their angle, Eddie would continually try to make Chavo adopt Eddie's cheating tactics, but Chavo often refused to do so.
On the March 9, 1998 edition of Nitro, Chavo lost to Booker T in a match. After the match, Eddie suplexed Chavo to teach him a lesson. On the March 12 edition of WCW Thunder, he defeated his nephew Chavo in a match and forced him to become his "slave". At Uncensored, Chavo was forced to support Eddie when he faced Booker T for Booker's WCW World Television Championship. Eddie lost the match after receiving a missile dropkick]]. Eddie and Chavo then feuded with Último Dragón. Chavo lost to Dragón at Spring Stampede. At Slamboree, Eddie defeated Dragón despite interference from Chavo. After the match, Chavo kissed Eddie and began to display insane behavior. Eddie would leave Chavo during a match, and that would lead them to feud with each other. At The Great American Bash, Chavo got an upset victory over Eddie. They faced each other in a Hair vs. Hair match at Bash at the Beach which Eddie won. Continuing to show his crazy behavior Chavo would shave his own head while Eddie looked on in disbelief. Eddie saved Chavo from beatings by Stevie Ray, seeming that he would align with Chavo but he wanted his release. Chavo's treatment at the hands of Eddie drove him "crazy" and he adopted the gimmick of a psycho fixated with a hobby horse he dubbed "Pepé." This led to a feud with Norman Smiley in which Pepé was thrown into a woodchipper by Smiley. Another result of his insanity, was his inability to join Eddie's Latino World Order stable, which was a take-off of the nWo. The stable included nearly every Latino wrestler in WCW except Chavo.
World Wrestling Entertainment (2002–2004)
Los Guerreros was the official name of Eddie Guerrero and Chavo Guerrero when they were a tag team in World Wrestling Entertainment. This Los Guerreros formed sometime during 2002 following Eddie Guerrero's jump to the SmackDown brand. Eddie had been Chris Benoit's tag partner on Raw, but Benoit turned face and moved into a feud with Kurt Angle while they were a tag team on the side. Eddie and Chavo ended up teaming up as a heel tag team when a tournament was announced to crown the first-ever Tag Team Champions, then a new belt just being introduced. Los Guerreros defeated Mark Henry and Rikishi to make it to the semi-finals where they lost to Angle and Benoit.
The tournament ended with Benoit and Angle beating Edge and Rey Mysterio becoming the first-ever Tag Team Champions. Edge and Mysterio won the titles afterwards. At Survivor Series 2002, Los Guerreros defeated Benoit and Angle and Edge and Mysterio in a 3-Way Tag Team Elimination match to win their first WWE Tag Team Championship. After facing makeshift teams consisting of Edge, Mysterio, and Benoit for a few months, they turned babyfaces to feud with John Cena and B-2, and Team Angle (Shelton Benjamin and Charlie Haas). They would lose the tag titles to Team Angle on February 6, 2003 edition of SmackDown!.
Eddie later teamed up with Tajiri to win back the belts due to an injury to Chavo. Team Angle, by now known as The World's Greatest Tag Team, won back the belts but Chavo returned a few months later. On September 18 edition of SmackDown!, they defeated World's Greatest Tag Team for their second WWE Tag Team Championship. They would lose the belts to the Basham Brothers about a month later, leading to a storyline spanning several months in which Chavo eventually turned on Eddie, breaking up the team. Eddie then ascended to the main event by becoming a WWE Champion. Eddie and Chavo were last seen at together at Judgment Day 2005 when Chavo tried to interfere in the match between Rey Mysterio and Eddie Guerrero.