found some more info
http://melbournepinballclub.com/LeagueRules.html


Here is some info I found on pinside used by pinball leagues in the states.
We seriously have nearly 70 people in the Pittsburgh Pinball League and we play EVERY WEEK during the 8 week season (3x per year). Players can pick from 3 different days each week to play. We started out with a public location that had 4 games as a regular Thursday night spot, Friday nights are hosted by a different collector (4-50 games) each week and Sunday afternoon is at another public location. Players are randomly assigned to groups of 4 and pick game or order-of-play based on what order they were drawn. They play on 3 machines for the standard 4-2-1-0 points system (ie, a 12 is a perfect night). At the end of the season points are totaled and the top 16 go the A finals, the lower 16 are in B and the rest in C. The average league night takes several hours with plenty of social time. Finals takes 10-12 hours on one day... with plenty of social time.  The top 4 in each division are awarded cash and trophies. There are also 'door prizes' including a free MACHINE given away each year (this year is WCS94). Dues are $20 for the season. There's plenty more to the details, but that's the basics.


here is some more.
The bare bones of league play in BAPA is as follows:

1. Players are organized into four player groups or as close as possible.

2. Four games are played each league night, order of players is rotated each game so that no player gets an order advantage. There are times when people have to wait for games. People socialize, or play non-league games. It's not a problem.

3. Extra balls are not really played. You get to plunge the ball and flip it once. After that, you have to stop playing. (An EB can still be a game changer on games which carry over bonus). Also, if your one flip starts a video mode, or mini pf mode (Battle the Power, Stewie Pinball, etc) you are allowed to play those out.

4. Scoring is 1st: 4 points, 2nd: 3 points, 3rd: 2 points, and Fourth: 1 point. This is different than tournament finals scoring, which is often 4-2-1-0. Giving last place a "pity point" keeps things more friendly to newbies. Nobody wants to end the night with a fat zero.

5. The groups on the first night of league are random. If you do well, you will be paired with the players in other groups who did well. Each week you will be moved into a group with people who scored similarly to you. Thus, in a night there might be a big skill disparity, but over the course of the league season, you will eventually end up in groups reflecting your skill.

6. In cases where there are only 3 players in a group, whether or not players finish 2nd or 3rd is determined by if their score is above or below the median score for all players. The scoring is computerized using smart phones, so the median and proper scoring happens automatically. For most leagues starting out, it's probably fine to just score people 4-3-2 because your odd number groups will be your newbie players, and a few extra points is likely not going to make a huge difference for them in the long run.

7. You have to attend 5 league nights (out of 16) to be eligible for the playoffs. Your performance during the league nights determines where you are seeded in the playoffs.

8. League starts at 8pm. Many people show up an hour earlier to warm up or socialize. A typical league night goes until around 10:30 for the lower skilled groups and 11:30 for the top groups.

9. Four games doesn't seem like much, and for some, it might be possible to make it five games, particularly if some are EMs. However, if you have decent players, four games is plenty.

10. Playoffs is a double-elimination bracket. In BAPA, the bracket is played all the way out and all ties are resolved. It's an all-day affair and a potluck kind of event. Here is the bracket:http://www.bayareapinball.org/elim32.html

11. Another useful piece of software is ALJ Tournament Maker. It's free.

12. The league uses a public location but also some private. The general rule is you have to attend one night at the public location before you can go to the private ones. Some people are especially lonely and/or shower-adverse, and/or not yet ready to accept their lactose intolerance. You don't want these people in your house.