Which is another reason to restart Secret Avengers like yesterday.
Madame Masque for Kate specifically.
Other than her those two don't have a specific Villain when teamed up.
They've taken on Tracksuit Gangster, Masque, Hydra, AIM, some shadowy collaboration of Villains that included Kate's dad, Vampires, Landsharks, Modok, mindcontrolled giant size Tigra, all the other Marvel Marksmen but apart from the aforementioned lady no one stands out really.