If I may throw in my two cents on this, I went on one forum before this one for ASB a long while ago. That forum has long since closed their ASB section, and so I don't go on there anymore, but they actually used this Reffing Calculator, and it's pretty easy to use.

It does calcs for damage and energy separately, and it takes into account base power, evo stage, typing, stat changes, and even CRITICAL HITS.