
Clearly, Primus and Unicron would be orders of magnitude larger than anyone pictured here, so they're not shown.
I've always considered guys like Metroplex, Fort Max, Trypticon and Skorponok to be roughly the same size... with Fortress Maximus and Metroplex being the tallest, as they stand up straight like a humanoid.
After that, things get a little confusing. Let's assume, for a moment, there is no mass change when transforming. Omega Supreme would need to be large enough to fit several autobots inside his alt form with ease, but small enough that combiners such as Devastator would still pose a threat to him. But one must also consider that each constituent arm/leg/torso of a combiner must fall into the "normal-ish" size range for cybertronians.
Thoughts, comments or suggestions? Should one or more of these bots be drastically larger or smaller?