Psicosis

In 2005, Castellanos signed a contract with WWE. He appeared at the WWE-promoted ECW One Night Stand pay-per-view on June 12, losing to Rey Mysterio. His first WWE television appearance was on the June 18 airing of WWE Velocity, teaming with Super Crazy to defeat Akio and Billy Kidman.
Psicosis, Super Crazy, and Juventud would group together to form a faction known as The Mexicools. The group made their debut as heels on June 23 when all three members rode to the ring on a John Deere lawn mower, with the sticker saying Juan Deere to be more Mexican, wearing matching coveralls and attacked both Chavo Guerrero and Paul London during their WWE Cruiserweight Championship match.
Juventud cut a promo questioning the lack of "true Mexican Luchadores" in the cruiserweight division, before going on to deride the current state of Mexican Americans in general. Psicosis dubbed the lawnmower they arrived on a "Mexican Limo 2005" and the group claimed that even Mexico's President mocks Mexicans in the United States (he was referring to Vicente Fox's controversial remark that Mexican immigrants do the jobs "not even the blacks want to do"). Juventud then stated that they were "no longer there to clean toilets and work for "them" (the "gringos") but "they" were going to be working for "us" (The Mexicools)", before dubbing the team "not Mexicans but Mexicools!" In the following weeks, they would continue to make run-ins in matches and mock the stereotypical image of Mexicans in the United States, even coming to the ring each with their own riding lawnmower.
On July 24 at The Great American Bash in Buffalo, New York, they defeated the Blue World Order in a six-man tag match when Psicosis pinned Steven Richards to secure the Mexicools' first PPV win. The trio then turned face by feuding with Nunzio and Vito. During the December 2 edition of SmackDown! Super Crazy and Psicosis won a battle royal with 5 other tag teams, earning a match against MNM at Armageddon 2005 for the WWE Tag Team Championship. MNM lost the titles before their match, however, which meant that the Armageddon match was just a standard tag team match. During the January 27, 2006 edition of SmackDown! Super Crazy and Psicosis defeated The Dicks (Chad Wicks and John Toland) and the F.B.I. in a three-way tag team match to win spots in the 2006 Royal Rumble match on . Psicosis entered at Number 4 in the Royal Rumble match, but was quickly eliminated by old rival Rey Mysterio.
During mid-2006 the ECW brand was revived and with this came the expectations that Super Crazy would leave Psicosis and SmackDown! for the new ECW. This was later fueled with a match that would see Yoshihiro Tajiri and Super Crazy team up and face the F.B.I. at One Night Stand. At this time, Psicosis' partnership with Crazy began to crumble when Psicosis repeatedly abandoned Crazy during incidents with The Great Khali. The team would soon split with Psicosis turning heel. Psicosis' match against Super Crazy on July 21 on SmackDown!, which he lost, would be his last televised WWE appearance.
WWE.com officially confirmed Psicosis' release from his WWE contract on November 1, 2006 after he was arrested.