Which of the following Elite Four members from the 6th Generation of Pokémon was a member of Team Flare?

The answer is Malva because she was a member of Team Flare, an antagonistic organization in the 6th generation of Pokémon games. Malva is one of the Elite Four members in the Kalos region and also serves as a member of Team Flare, indicating her involvement with both groups. As a member of Team Flare, she actively works toward their goals of achieving ultimate beauty and making the world a better place for themselves. Thus, Malva's unique position as an Elite Four member and Team Flare member solidifies her as the correct answer to the given question.