Enfys is not invincible on the first hit she takes after her turn. Time your big hits for right after she goes. Keep her stunned or dazed and she can't counter attack. Geonosions, Troopers (if you are careful with you timing and don't use Piett or have Starck zeta), and other teams with heavy hitters (not CLS though)
Do not reduce her turn meter, she has to take a turn for you to kill her.
Then, of course, there are toons like Darth Nihilus and The Mandalorian who can straight up destroy her regardless.
Or use Jedi Knight Revan, or any toons that reduce max health.
Really there are lots of ways to kill her