it's easy to beat them, all u need is Jecht's Shot and luck.
the first period, don't let them get any goals, keep the ball away from them (perverts...)
next period, set Jecht's Shot to Tidus, get to the goalkeeper with mostly 2/3 after u, when u reach the goal just press Square and use it, then keep the ball from then untill the time is up and u've won and earned a Strength Sphere +4