I'm assuming that by in Mount Lanakila, it means you level Crabrawler up at that location. Is that right, also, unrelated question, what is the interaction to get a Wimpod, where is it? Thanks in advance!
That's correct, you must level Crabrawler up at Mount Lanakila. The same is also true for other location-based evolutions, like Charjabug to Vikavolt in Vast Poni Canyon and the like. Wimpod can be found on Route 8, Poni Breaker Coast, and the Poni Wilds. It can be cornered pretty easily by using Tauros or Sharpedo.
Hope I helped!