If you know attacker’s (Special)Attack, defender’s (Special)Defense and damage done?
(Asking because of Hidden Power)
Pleaselog inorregisterto add a comment.
This is the formula for damage. So, you would fill in the spaces that you know, and after that, it is simple math to find out the base power. Or in your specific case you could get your Pokemon to level 50 or 100 then use an IV calculator to find out the IVs and Hidden power. Or if you are in Gen IV then you can do a Lvl. 100 Single instead of levelling up.
Source
EDIT: As DT mentions in the comments, part of the modifier is a random number from 0.85 to 1.0. So this won’t be reliable, but you can run it a few times and take the average.
Http://www.psypokes.com/dex/hp.php
use the calculator ^.^