Just go in from the *entrance northwest from the surfing entrance, you should be in citrine mountain F1, then on that floor go east and just surf. You should find it pretty fast.
*From celestinine cascade that is
The makuhita trainer is in apophyll, middle room to the left of the central field of the academy. Then the roggenrola (mcsomething) guy is in spinel town.
I released the roggenrola i need to complete the DJ Arclight quest, so if anyone can trade me the roggenrola needed for this quest, I have a few shinies in exchange.
Thanks!