There are 3 moves I recommend you replacing Superpower with Conkeldurr, Mach Punch, Bulk Up or Drain Punch.
These for moves are by far much better then Superpower as making it drop in both attack and defense is a true waste of time and energy
*Mach Punch is one of those reasons why that Conkeldurr is one of the best Pokemon around and outclasses Throh. This Strong STAB move will be doing a lot of damage if you would combine it with Bulk Up. It also makes up for Conkeldurr's ridiculous speed stat and will enable it to hurt or in some cases KO a Pokemon before it can act
Bulk Up is that move that makes Conkeldurr an absolute monster. Boosted by Guts, Conkeldurr will be dessimating everything that comes it way after just utilizing this move once. Not only does it boost Conkeldurr's Attack, but defense as well. Bulk Up is definitely a move that Conkeldurr should have
This powerful move usually goes with the 2 moves listed above but it can perfectly be used on your current moveset. It will take a chunk of HP from your opponent, whiles recovering yours. This move should be the best substitute for Superpower :)