Ability Points are obtained from enemies after they are defeated. Ability Points will give you the opportunity to chain various element types together. The more elements that are chained, the higher the Ability Point cost. You can create very high damage combos by spending a lot of Ability Points when there are elements of every type on your board. Save your Ability Points for tough enemies or Bosses. You will begin each level with about 5 Ability Points and earn more over time.
Allies
Before a level begins, you will be given an option to bring along a random player's leader as an ally. Try to always do this as this will result in 5 friendship points being earned. Those points are spent to summon new allies. Additionally, after the level ends you can send a friend request to the person you played with. If they accept your request, you be able to take them regularly as an ally and earn 10 friendship points each time.
Crew
You can have up to five people in your crew at one time. Four of them will be members and one as their leader. Some characters allies have "leadership" skills. When given the leader position, those skills will become active. Leadership skills are usually some type of stat booster. For example, when a Sun Knight is a leader, his skill powers up Sun-type allies. If a character does not have a leadership skill, do not designate them as the leader. When you have certain characters on your team at the same time, they will form a "crew combo". They convey passive buffs, similar to the leadership skills.
Elements
Each element has an opposing element that it is stronger against. Fire is stronger than Earth. Earth is stronger than Water. Water is stronger than Fire. Sun and Moon are neutral to each other. Attacking an enemy with the same or neutral element will result in slightly reduced damage. Attacking with an element that they strong against, for example using Earth against a Fire element will result in reduced damage. Attacking an element that your enemy is weak against causes slightly increased damage. Manually target enemies in order to send your attacks to a specific enemy.
Stars
Each level has a total of three star that can be earned. The first star is earned by completing the level. The second star is earned after the Boss of that level is defeated with your HP above a certain percentage. The third and final star requires that the level be completed under a certain time limit.