You can never go wrong with implementing a purity system. Let her Start out innocent and "discover" her naughtier side.
Might be a little more ambitious then what you were going for but it'll help the game to not feel so much as a Linear Visual Novel.
Also, btw your name change to "Punkmon" really bothers me.
You were better off with the way it was but if you must change it, "Pmon" is a LITTLE less annoying. Or "PKmon" or something.
These are both very good ideas.
So I thought instead of making her behavior less slutty, which is virtually unavoidable for what I have planned, maybe I should make her dialogue and reactions less innocent/air-headed and a little more naughty in the other scenes, therefore giving her a more consistent personality. What you guys think?
It's your choice, the issue you are going to have is that it will be literally impossible to please everyone with this, ur gonna upset some people no matter what you decide.
Personally, I would prefer her to keep her innocent side, but I don't know what you have planned, so I can't really say!