Started out in AAA in 2004 as Javi, one of the Kumbia Kids. The group got a big lead up but most of the members didn't stick together too long. Javi & Jesse were kept the outfits as a rarely seen opening match card tag team. In 2008, they were briefly restarted as part of a Nuevo Barrio Boys group, but leader Alan was pulled away from the group and the others went back into limbo.
Nemesis turned up as a regular in AAA in 2006 as part of Real Fuerza Aérea AAA, but disappeared during the 2007-08 winter break. It's very possible AAA thought they had one too many Fuerza Aerea types and he was an easy one to replace.
Since 2008, Javi/Nemesis seems to be switching back and forth between characters depending on whatever is needed at that point. The Nemesis identity is more well known because of more television exposure, but Javi turns up more in lineups currently.