Since there is no way for me to know if its in-game or not ill answer. If it is metagame and you are in the OU tier then you could use either. But if it is UU tier then you have to use Scrafty from these choices.
Conkeldurr
This guy is godly if you set him up right. He has more Attack and HP then Scrafty and it can make for the lower defense with Bulk Up. It would definitely have a lot of bulk and attack making it the perfect candidate to sweep a team. Pair him with Guts and Flame Orb to add even more attack. Or you could give it Leftovers so it can survive longer. Thats a matter of choice. If you decide to go with this guy here is a link to his moveset question so you can find one that fits you or get some inspiration.
Scrafty
He is IMO under-rated at what he does. Since this guy has Dragon Dance you could easily sweep a team with it. It gets Moxie which is a great ability. Anybody with it could sweep a team. Trust me if he gets of a few Dragon Dances up and it has Moxie you team will probably be swept unless you get stuck against one of its many counters. There is a reason its UnderUsed. But he is one of the best Fighting types of the UU tier. He has more Defense, Speed, Special Attack, and Special Defense than Conkeldurr but that doesnt make it better. Here is moveset question for this guy incase you want to check it out.
Short Summary for the lazies: If its OU go for Conkeldurr if its UU you have no choice but Scrafty(Of course only if these two are you only choice, but i would still choose scrafty over the other UU fighting types.(Thats just me)
