Custom Points: This system allows you to determine how many points are awarded for playing a match, winning a match, set, or even a game. You can also deduct points for a loss or award more points for winning in straight sets or a higher ranked team.
Elo Rating: This system is the best system for ranking teams by their ability. Each team will start with 1500 points, which will increase as they win and decrease as they lose. The amount of points gained or lost from a match is dependent on the points of the opponent played. For example, if a 2000 point team beats a 1000 point team, very little change will occur to either teams rating. However, if a 2000 point team loses to a 1000 point team, both teams ratings will change drastically. Teams points will also change more drastically during the first games that are recorded. This allows teams to reach a stable equilibrium quickly. Learn more here: http://elorankings.com/
Leap Frog: This is the most basic and simplest ranking system. When a lower ranked player beats a higher ranked player, the lower ranked player "leap frogs" over the higher ranked player, pushing them and each player initially between them down one spot. If the higher ranked player wins, nothing happens.
Leap Frog Plus: This system is the based on the classic Leap Frog system, but also awards additional points based on games won and lost. This rewards players with points regardless of the outcome, and encourages more play. Here is how it works:

If you play a best of 3 set match, there are 39 addition points awarded in addition to leaping (or not leaping). This is because 39 is the maximum number of games that could be played in a 3 set match (7-6, 6-7, 7-6). The loser always gets 1 point for each game they win, and the winner gets the rest.

Lets say team A is ranked #1 and has 200 points, and team B is ranked #5 and has 150 points. Here are two sceniaros to help see what could happen:

1. If team A wins 6-1, 6-2, they would then have 236 points, and team B would have 153 points.
2. If team B wins 6-4, 6-3, they would then have 232 points, and team A would have 207 points.
Manual Points: This system allows you to manually enter the amount of points a player or team receives or loses for each match, forfeit or even declined challenge. Using these points, the sytem will automatically compute and update the rankings.