To unlock Charley Marshall, the player is required to complete all research projects. This challenge is unlocked from level 1. Unlike most challenges, moving to the next level does not reset the progress.
The "revamped" Marshall is substantially less useful than the original character. He loses two useful skills, Powerhouse and Chemistry, only gains Research in return. However, given the fact that research projects carry over from one level to the next, by the time the player gets him, they will have very little use for this skill, and this hero character can offer very little to the community.