This article is from the Pro-Wrestling FAQ, by firstname.lastname@example.org (Dominic Macika) with numerous contributions by others.
Well, there are many rules, differing with the type of match that
is being wrestled (singles, tag, 6-man tag, special
stipulations), but here are the basic rules for most Lucha Libre
* most matches are trios matches, which are known in the U.S.
as 6-man tag matches
* in trios matches, there are usually 2 referees. Generally,
one is a heel referee and one is a face referee
* most matches are 2 out of 3 falls
* one member of each team is designated as the captain
* when a wrestler is knocked out of the ring, one of his team
members can enter the ring without tagging
* a fall in a trios match is won when the captain submits or
is pinned, or when the other two members of the team submit
or are pinned. This frequently leads to falls ending when
three wrestlers are pinned simultaneously.
This might not make much sense to some non-Lucha fans but that's
the way they wrestle Lucha style and they've been doing it this
way for decades. Lucha fans don't even think twice about it.