1=Normal 2=Fire 3=Water 4=Electric 5=Grass 6=Ice 7=Fighting 8=Poison 9=Ground 10=Flying 11=Psychic 12=Bug 13=Rock 14=Ghost 15=Dragon
How it works... Take your Pokemon and find it's type. Now find the number on the left. Find the kind of pokemon on the top that you are attacking. Now follow it down and where the two numbers meet is your chances of winning. But remember, if the enemy Pokemon is about 15 levels higher, you can be pretty sure you will lose.