There are 100 different blending combinations for RGB, according to the ShaderLab documentation on blending. That is, there are ten "properties" to multiply both the pixel that is currently being renderered, and the one that is in the color buffer, by. On top of that, there is an undocumented ability to blend only the alpha channel result, like so:
// no RGB blending, multiply the alpha channels together
Blend One Zero, Zero SrcAlpha
// should be the same, because only the alpha component is blended
Blend One Zero, DstColor Zero
In my experience, they all work in the Editor, under any emulation setting. However, some of them can yield incorrect results on iOS devices. Which ones don't work, and why?
Multiplying a color by itself, or its inverse, results in the blending operation being cancelled. For example, each of these will result in no blending:
Blend Zero SrcColor
Blend DstColor SrcColor
Blend DstColor One
Blend OneMinusDstColor OneMinusSrcColor
MBXlite and SGX
If you don't change the default frame buffer setting (RGB565), then you can't utilize alpha from previously rendered materials. DstAlpha will always be treated as 1, and OneMinusDstAlpha as 0. You can change this by selecting "Use 32-bit Display Buffer under" the "Resolution and Presentation" section of Player Settings.