BUT I do want to change one thing about the system, to add a little realism. Pokemon are able to use moves that are of a different type than their personal typing, right? Well, from now on, move-type is considered when battling an opponent (not just the two Pokemon's inherited types). This adds a little more realism, but at the same time, it does not complicate things much for me. 

Your Pokemon's roll is now effected thusly:
+50% for using a move-type that matches the Pokemon using it
+50% for using a move-type that the opponent is weak against
-50% for using a move-type that your opponent is resistant against