There is no legitimate way to evolve it without trading.
Boldore evolve from trading into Gigalith.
Roggenrola evolves into Boldore at level 25. You can evolve Boldore into Gigalith by trading it.
Boldore,Timburr,Shelmet And Karrablast
Boldore evolves when you trade it.
Yes, you can still evolve that Boldore into Gilgalith.