Football manager game problem

i have decided to make a fantasy footie manager game though it will be very very basic at the start, i am using arrays to take in the teams, this in turn is broken down by more arrays to show the players of each club. my problem is that i dont know how to compare the teams playing each other (i.e. player ability shooting speed etc.) and i also want to incorporate a program that will give random results after all that is taken in to consideration as the big teams dont always beat the weaker one's. if you have any views on this can you post a reply or email me, address in profile.