I took a look at a map by Loveless that shows how to stack units by the use of sprites and changing their properties.
I've tried several different units that have worked, but Archons do not seem to stack.

I have tried checking/unchecking just a few different properties. All the other units I've tried, that worked, used Blocks view??, Flag 10, Two states??, and Disabled??

Would an Archon need a different set of boxes checked, or does it just not stack? Also, does anyone know what flags 2,3,4,6,7,10,11,12, and 15 do?

In my experiences, I've only been able to get a few units to stack...

Disabled and Draw as Sprite are the only used flags.

Archons crash when placed as a disabled sprite, as you can see here. Even if they don't crash when placed, many units just crash when enabled, it's a pretty unstable system, and I've found that it varies slightly from map to map, what it comes down to is just testing it out and seeing what works for you.