[KenWittlief]

sure you can make a shifting transmission, but you cant defy the laws of physics

a light robot that has low inertia wheels (thin wheels) can also be built with a lightweight shifting tansmission

a robot with wheels or treads designed to have a lot of pushing power must put big treads on the floor, and it will weight more, have more inertia in the wheels and drive train, so motor for motor it will be slower and harder to control. An Abrams tank can go 60mph, but it cannot corner like a race car.

Besides, the rules clearly state you cannot fly across the field and slam into another robot, so if you do have a fast dozer bot, you cannot zip across the field to push another bot around, unless you stop first (and downshift).

A bull can outrun a bullfighter, but the bullfighter is able to step out of its way.