Pyro is correct. Every Mexican ping will change its leaf form throughout the course if its life. Whether or not it actually produces true succulent, non-carnivorous leaves or just much smaller leaves with carnivorous glands depends mostly on individual growing conditions. As a rule, the dryer they are kept the more likely the leaves will be succulent and non-carnivorous. There are some forms which, if kept consistently damp, will merely produce smaller, carnivorous leaves. However, even those forms which still produce small carnivorous leaves no longer seem to actively capture prey (they do occasionally, but it is a relatively rare occurence).
The only Mexican form in which I have never observed a change in leaf form is Pinguicula emarginata. I am not saying that P. emarginata does not change leaf form, just that I have never seen it.