All Brass Instruments Have Marching Band Models
Is the tuba too big and heavy to be a part of marching bands? No, it is not. That is what the marching tuba is for. As you can see in the photograph, a marching tuba is held horizontally, not vertically, and played with the bell facing forward.
In addition to the tuba, marching band versions of the baritone, horn, and trumpet are also made. The design is lighter in weight and takes into account the player's need to look forward while marching.
Have a listen to a phrase played by the marching baritone in Sousa's Stars and Stripes Forever.