Deoxys EX damage addition

[Spirit Of Mew]

I want to make sure I'm clear on this in case I make any rulings on it in the future.

If I use an attack by a plasma pokemon that does X damage times a factor of some sort (30 x the number of heads you flip in a row or something similar) does Deoxys's ability add to the base damage or post damage?

For instance, if I had 3 deoxys on my bench and used the above example attack would it do 60 times or 30 times whatever number plus 30 additional for deoxys?

 

[PokePop]

It works just the same as PlusPower. The addition is done AFTER all attack calculations are done, so it would be +30 in your example.
Note, though, that if you got zero heads and the base damage is 30 x 0 = 0, then nothing is added. You have to do some damage before an effect can increase it.