hello Asmo,
well, we have many stages of sparring and many different sparring "games" in our school - on the spot; with turning; with steps; strikes only; grappling only; strikes and kicks; strikes, kicks and grappling, tui shou/chi sau kind of "sparring" (man kiu). most of those are part of methodical and systematical preparation for the complete thing, ie. strikes, kicks, grappling and locking (tek, da, syut, na).
in my opinion, it is very important to train 2 different ways:
a) everything goes - even eye gouges, hair pulling, throat strikes, groin strikes... but slowly, just touch is ok. this type of sparring is meant to train whole range of techniqes we have
b) full contact, with full protective equipment. this type of training trains the real speed, power, aggressiveness etc.
anyway, both for school and out of school gong sau matches, we have this basic set of rules:
1) fair play!
2) 18 years+
3) fighting "ring" - cca 3 m in diameter, made by other guys standing in a circle
4) no weight divisions
5) mandatory minimum protection gear - mouth piece, grappling gloves, cup. any ther protection gear is up to the two guys having a bout (boxing gloves, headgear, shin protecors... )
6) clothing - light shoes, ppants, t-shirt. no heavy boots, rings, chains, bracelets, ear-rings etc. if the figther want to use kicks to the head, he has to fight barefooted.
7) referee - 1 neutral, plus each fighter is coached by one guy.

time - 2x2 minutes.
9) forbidden techniques - attacks to the eyes, palm strikes to the ears, fishook, throat strikes, groin strikes. all the other techniques (elboes, knee kicks, fight in the clinch, throws, ground fighting... ) are arranged between the two guys and their couches before the match
10) end of fight: the bout could be stopped by coach, fighter (tapping out, loud shout "stop!"), by using of forbidden technique.
11) victory - not decided, everybody knows. we do the matches to have more experience, no prices