Super #17 was kind of a “transformation” specific to him, kind like Cell’s forms. It’s because he, as a character, was designed to gain a new form with greater power when absorbing his counterpart, much like Cell absorbing #17 and #18.
However, a powerful alternative could be breaking their power limiter, as all androids built by Gero have them. It would be a temporary, but tremendous, power-up with the cost of the user’s life (or just a big chunk of health for an easier time).