In terms of health, damage and range, Medu-san is actually weaker than her Traitless counterpart. Even her Lv.1 Surge Attack doesn't allow her to reach any farther than Mr. Mer with his Mini-Waves.
She has 20 less range than Mr. Mer, leaving her open to being frozen by a TalentedWeedwacker Cat, though you may additionally have to unlock Resist Surge for him to stand a chance against her. Other options include fully Surge-immune Cats such as Talented Gato Amigo as a meatshield and Talented Beefcake Cat as an attacker. Even Cats that can outrange Medu-san's regular attacks can still potentially get hit by a Surge depending on where it spawns.