Here is a combat chart to help you out in battle. One the left side, look for your pokemon's type or attack, and on the top look for your enemy's type. If you do not know your pokemon's type, you can look in my Complete Pokedex.
If the box is blank where the two meet, the pokemon are evenly matched. If there is an 'A' you have the advantage, and a 'D' means you have the Disadvantage. An 'X' means there is little hope of you winning. This of course only applies if the two pokemon are around the same level.