What stone do you need to make piplup evolve?

oh no stone...you just need to train it to a certain level...if your talking about platinum its either 14 or 16 i think...hope i helped oh PS...do you like my team?grotle nickname twiggy lv28...gyrados nickname rex lv25...drifloon nickname Tina lv23...gible nickname jaws lv23...jolteon nickname strike lv22...:) :D