Where can you find medicham in Pokemon platinum?

you can find a medicham on the victory road leading towards the elite 4. You can also find one in mt.cornet. The final place would be on iron island. A girl will challenge you as part of a double battle once you team up with Riley. She will have one. Also if you go to iron island Riley would like your help and once you find the exit he will give you a riolu egg, so take only five Pokemon with you. (riolu envoles into lucario)