For those who don't want to read the link, here's the bullet list of the rules they're testing:
New rules to be tested out in the Arizona Fall League after recommendations from MLB's pace of game committee:
• Batter's box rule: Hitter required to keep at least one foot in the batter's box throughout at-bat unless there is foul ball, wild pitch or passed ball -- or if a pitch forces him out or the umpire grants "time."
• No-pitch intentional walks
• 20-second rule: 20-second clock will be posted in each dugout, behind home plate and in outfield to prevent pitchers from taking too much time in games at Salt River Fields only.
• 2:05 inning-break clock: Maximum time allowed between innings, and batters must be in box at 1:45 mark or umpire can call automatic strike. If pitcher throws pitch after 2:05, umpire may call ball.
• 2:30 pitching-change-break clock: Maximum amount of time allowed for pitching change.
• Three "timeout" limit: Teams limited to three trips to the mound by managers, coaches and catchers during game, except pitching changes.