hmmm, i've checked both my comrefs and i'm not seeing an 'ALL' keyword...
what you can do is make a trigger which covers the whole map which is triggered by one side, and in the on activation box put
number_of_loons = count thislist
untested, but i'm pretty sure that's the syntax. thislist will keep a dynamic record of how many units of that side are on the map. if you want to check for the beginning total, i.e. a static number, use '+thislist'.