taken from Wikipedia:That could be interesting. Though I'm not sure how I feel about drawing from two totally different mythologies for the same line of Pokemon... However, I THINK the same thing Mawile is based on (futakuchi onna or something?) had prehensile hair. Stretch it a little and say the prehensile hair also has mouths on it and I think it would be believable.
"Though there are several stories linking the appearance of a futakuchi-onna's second mouth to different causes, it is most often linked to how little a woman eats. The soon-to-be futakuchi-onna is usually a wife of a miser and rarely eats. To counteract this, a second mouth mysteriously appears on the back of the woman's head. The second mouth often mumbles spiteful and threatening things to the woman and demands food. If it is not fed, it can screech obscenely and cause the woman tremendous pain. Eventually, the woman's hair begins to move like a pair of serpents, allowing the mouth to help itself to the woman's meals."
seems like a reasonable basis to use Medusa as inspiration (of course, a passing comment on Wikipedia isn't much of source when it comes to Japanese folklore)... man, I'm really starting to dig this idea now. *_*