Note: This commands are for version 1.8+ for now, I'm not too familiar with commands from version 1.9 onwards. I apologize if these commands have caused you some unnecessary trouble.
Basic scoreboard commands
scoreboard?<objects|players|teams> Basic commands for the scoreboard system.
scoreboard?objectives?list lists all the objectives that exist, along with their display names and guidelines.
scoreboard?objectives?add?<name>? <criteria>? [display?name...] Creates an objective with an internal name of name, a criterion of criteria, and optionally a display name of display?name. display?name defaults to name if it does not exist. The meanings of the above components have already been mentioned. All parameters are case sensitive.
scoreboard?objectives?remove?<name> Removes all content related to objective name from the scoreboard system. The list of objects, and the player score data are removed, and if the object is on the display list, it is no longer displayed.
scoreboard?objectives?setdisplay?<slot>? [objective] Displays score information for the target objectives at the specified location slot. Legitimate locations are listed and described in the display location. Note that the parameter objective is optional; if no objective is provided, the display location will be cleared (back to default).
scoreboard?players?list?[playername] displays all players tracked by the scoreboard system. The optional player name parameter can be used to display all scores for a given player, and putting an * (asterisk) in playername will display all players being tracked by the scoreboard.
scoreboard?players?set?<player>? <objective>? <score>? [dataTag] Sets the player player's score on the objective objective to score, and overrides it if a score already exists. * Can be used for player items to represent all players being tracked by the scoreboard.?
scoreboard?players?add?<player>? <objective>? <count>? [dataTag] Adds the player player's score on the objective objective as count. * Can be used to represent all players being tracked by the scoreboard.?
scoreboard?players?remove?<player>? <objective>? <count>? [dataTag] Deducts the playerplayer's score on the objectiveobjective by the amount count. * Can be used to represent all players being tracked by the scoreboard.
scoreboard?players?reset?<player>? [objective] Removes one or all of a playerplayer's scores. If an objective is specified, only the score for that objective will be cleared; otherwise, the player's scores for all objectives will be deleted. Note that this is more than just setting the score to 0: the player will be removed from the scoreboard in its entirety (or from the given objective). * can be used to represent all players being tracked by the scoreboard.?
scoreboard?players?enable?<player>? <trigger> enables a player to use the command /trigger on the specified triggered target trigger. until this is done, the player will fail when using /trigger on the target. Once the player has used /trigger on the target, the target will become inoperable again. *can be used to represent all players being tracked by the scoreboard
scoreboard?players?test?<player>? <objective>? <min>? [max] Output when the playerplayer's score on the objectiveobjective is between the minimum value min and the maximum value max (both numbers included).? If not specified or if * is used, max defaults to 2,147,483,647. using * for min represents a value of -2,147,483,648. * can be used to represent all the players being tracked by the scoreboard
scoreboard?players?operation?<targetName& gt;? <targetObjective>? <operation>? <selector>? <objective> Uses the score of the selector on the target objective as input, performs an operation and takes the result as the score of the target player targetName on the target named targetObjective.
The arithmetic operation <operation>? can be:
"+="? Addition
"-="? Subtraction
"*="? Multiplication
"/="? Division
"%="? Dividing
"="? Assign
"<"? Take the smaller value
">"? Take the larger value
"><"? Swap selector and targetName scores.
Selector's score on objective will remain the same except for "><". *Can be filled in either targetName or selector (but not both) to represent all players being tracked by the scoreboard.
The objective and targetObjective must exist, the targetObjective must not be read-only, and all targets/selectors used must have scores on the corresponding target (if one has a score and the other doesn't, the arithmetic operation only succeeds if both the target and the selector have a score). Note that the ?targetName does not have to be online or even exist.