There are a few synonym options for the phrase "more flat footed" that may better suit your needs depending on the context. One option is "less agile," which implies a lack of movement or flexibility. Another option is "less nimble," which suggests a decreased ability to move quickly or easily. "Less fleet-footed" is another possibility, which means having a slower stride or movement. Additionally, "less sprightly" or "less lively" can be used to describe a reduced level of energy or vitality in one's movements. Ultimately, the best synonym for "more flat footed" depends on how you want to describe the individual's movement and abilities.