Achievements

Achievements are used to unlock characters. They can only be unlocked in Arcade mode. Each opponent has his own set of achievements, but you can get them with any character you want.

Achievements

 * Win without conceding a goal
 * Win by more than 10 goals
 * Win without using a power shot
 * Win 10 times
 * Win in a sudden death
 * Win without using a dash
 * Win with 5 Counter Attacks
 * Win without using a kick
 * Win without using a jump

Win without conceding a goal
You can look here for some advanced tactics.