This topic is rather silly, but it does raise a serious point:
falling. If a tyrant falls a dozen stories and lands on a dretch, the dretch should be crushed.
So basically, the way to do it would be to replace/generalize the current gravity/human splat stuff with damage for collisions that can be applied to everyone (preferably based on momentum -- or an approximation of it based on speed, direction, and size). Then tyrant charge and dragoon pounce could become just special moves. They would still do damage, but in a more general way.