Teams is is the people who you invite from your friend's list. For being on someone's team, you get twice the amount of experience points in boss fights. Also, the more team members you have, the bigger attack/defense boost you'll have (maximum is 25%), hence the importance.
- 1% Bonus with 1 person in your team
- 2% Bonus with 2 people in your team
- 5% Bonus with 5 people in your team
- 10% Bonus with 50 people in your team
- 15% Bonus with 100 people in your team
- 25% Bonus with 500 people in your team