Hey
Just wondering, when creating textures for particles and particle animation sheets, should you use a black background or a transparent background?
I tested both of them in Unity with the particles/additive soft shader and they seem to be the same, with the only difference that the transparent particle texture file is larger than the black one (67kb vs 38kb) and the fact that the transparent also has the flexility of being used elsewhere.
@Reactorcore, reviving an old post!
TL;DR; In your scenario, I’d commit to answering one should use the smaller file, as you point out the effect is the same.
For why I say this, and hopefully it helps future solution seekers as this effect is related to the solution I’ve stumbled on, I offer the following!
As stated above, one is using the Additive shader, which adds the color values of black (R: 0, G: 0, B:0) rendering it transparent.
Though, if one uses Multiply, Alpha Blended, etc. they may get the presumed expected result that would in fact show Color(R: 0, G: 0, B:0) as black, not transparent.
I encountered this phenomenon when attempting to create a smoke-y particle effect executed the same way it is in the Wind Waker installment of the Zelda series.
References:
Base Smoke Image: 
Additive vs Multiply Texture Shader: 