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In Japanese she calls it her "full power form" (zenryoku no sugata). The Japanese word for "full power", Zenryoku is where the Z in Z-move comes from, so that's why she does the Z pose. They called it her "Z-powered form" in English so the pose still makes sense.
There was also a pun used several types after she switched clothes, Ganbalillie, from the word "ganbaru" meaning "to do your best; to give it your all". Japanese often call her new form Ganbalillie.
