In regard to atk/def strength that you get to spend lvl up points on, if you had 1mil atk with an attack strength of 30 and a rival had 1mil def with a def strength of 20, you should constantly beat them 1v1.
There is a few discussions from time to time as to whether they are useful or not, but my theory on it is that whatever your atk/def strength is it should be multiplied by an exponential figure as to gain an advantage by putting points into them and make the game more competive between players stats.