here s the place for grinding before Crasher Wake
I'd say the Seven Stars Restaurant is a good place, since it has daily respawning trainers and you can train up multiple Pokémon at a time, since they're all Double Battles.
Seven Stars Restaurant is located in Hotel Grand Lake
the location of Hotel Grand Lake:
Hotel Grand Lake is technically either part of Route 213 or Valor Lakefront.
![](https://cdn2.bulbagarden.net/upload/thumb/f/f0/Hotel_Grand_Lake_Pt.png/300px-Hotel_Grand_Lake_Pt.png)
Hotel Grand Lake (picture from bubapedia)
![](https://cdn2.bulbagarden.net/upload/9/95/Seven_Stars_Restaurant_DPPt.png)
Seven Stars Restaurant (picture from bulbapedia)
Source and Source and Source and Source
Hope I helps!