Here are the 2018 Opening Day rosters for AZL Cubs #1 and AZL Cubs #2 as of Monday morning 6/18. Since both teams are based at the same location (the Cubs Under Armour Performance Center at Riverview Park in Mesa, AZ), moving a player from one AZL Cubs team to the other will be very easy and so it could occur fairly often (including anytime any day prior to game time).
All of the MLB clubs that have Spring Training in Arizona (except the Colorado Rockies) field at least one team in the Arizona League (AZL). Along with the Giants and the Indians, the Cubs have added a second AZL team this season.