I never have a problem with the Ewoks, usually they can only kill 2 men and than it's victory. First time with tusken vs. jawa I lost and later when I was better at the game I won big time on both sides. Gungans at the beginnig I won but was always real close and later when I got better, again no problems. For the jawa vs tusken there is an easy way to win on both sides: If youre Jawa get as close as possible and take out as many as possible.
If youre Tusken try to keep enough distance so that the Jawa's cant hit you but you can hit the Jawa's.
Thats all I can help with right now, I will play the other 2 again asap.