The simplest way is to divide the damage the attack does by the time it takes to make it. Literally "Damage per Second".
The best way is to calculate cycle DPS by using the fast attack enough to get a charged attack off, then make the charged attack, and take the total damage done divided by the total time it takes to make all the attacks.
So there can be variance based on how the DPS is calculated, as well as if they are taking STAB, Weakness/Resistance, and Weather into account.
