For my Bastiodon It knows
Toxic -Thunderbolt -Ice Beam -Protect/Earthquake It's role is Staller/Special/Physical Tank.
Go for Earthquake because protect isn't needed as much on a tank Pokemon which I guess is what you are using the Bastiodon am I right? Hope this helps :) ps: I have a level 100 Bastiodon and it is a baws along with Rampardos!