Hi. I think your team would benefit from using SD terrakion with rock gem over your current set. This allows you to capitalize on the damage that rotom and landorus build up together through forced switches. Rock gem allows you to 1hko gliscor who would otherwise stop your sweep.
I would also suggest using volt switch on forretress over toxic spikes. Your team is very offensively oriented, and you would benefit more greatly from being able to maintain your momentum with it.
Lastly, I think you would be better off using hidden power ice over hp fire on rotom. Your team doesn't struggle with ferrothorn at all, so having hp fire on rotom is a bit overkill. Hp ice gives you another answer to dragonite if it gets to +1 in case landorus is already down, because, otherwise, it goes to town on your team. (be sure to use 31 IVs so that you can speed tie with other scarf rotom)
Hope I helped! Good luck!