Misty's bionic arm is pretty powerful, but it's Colleen who tips the odds in the girls favor, imo..
She can chi amp enough to hang with Danny (Even if Danny was holding back, that's still impressive.), and learned K'un L'un martial arts, both from a mind meld with Danny. And she had to step in when Namor was having problems with Lei Kung the Thunderer.
She's racked up some other nice feats, like giving Steel Serpent some problems when he was toying with Spidey..