cappadocius

I've been working on a BRP-based Pokemon campaign for a little while now, and SIZ works just fine for the more typical biologies, those Pokemon that are, more or less, animals. However, I'm struggling with the appropriate SIZ assignations for the odd critters. For example, Bronzor, a solid metal disk that's 1'08" in diameter, weighs 133 pounds. SIZ 10 doesn't FEEL right for something only a little bigger than an LP. On the other side of the coin, there are the ghosts, such as Gastly, which is a gaseous sphere about 4 feet in diameter, but weighs two-tenths of a pound. SIZ 1 seems wildly misleading, and will significantly short gaseous entities on Hit Points. Has anyone worked out SIZ tables for non-organic life forms? If not, does anyone have some good rules of thumb for densities greater or lesser than human norm? I vaguely recall CoC 4th or 5th edition talking about how SIZ is more properly a measure of volume than mass, but also recall CoC failing to give any spot rules for how to work that in practice. Hit me with some BRP knowledge, folks. And please, no comments on how lame or not lame Pokemon are in *this* thread.