I thought I had the Vial too so I jumped mindlesly for quite some time. I also tried to put the Crustles to sleep with my own Pokemon.
You find out Side Ledges after trial and error, that's fine.
The thing that annoyed me was when you push down the Crustles, run down, quick save next to it, push the Crustle, make a mistake, then soft reset. And boom, for some reason the Crustle is on the upper floor and you're still on the ground.