I think Sawk is one of the best type-coverage Pokemon that is reliable in every case (in his tier). It can learn and use really good Electric/Ground/Ice/Fighting moves at the same time. Plus it has Mold Breaker! That gives him even more coverage + he can hit Shedinja, too! (It was the only weakness of the moveset. )
Only Pokemons in his tier those cause problem to him are some pure Psychic Pokemons. That can be solved with a dark Pokemon if you need. So here's the obvious moveset:
Sawk @ Shell Bell
Trait: Mold Breaker
EVs: Atk, Speed, Hp
Adamant (+Atk, -SAtk)
- Close Combat (Powerful STAB, it's okay to lower defenses since your aim is not to take hits)
- Earthquake (Mold breaker does the job)
- Ice Punch (Extra coverage + has a chance to hit 4x to some flyings those were problematic)
- Thunder Punch (Extra coverage + Water/Flying may heal you completely, he outspeeds all except Swanna)
I chose Shell Bell over Leftovers because Sawk doesnt have high HP and he hits hard almost everything. I think Shell bell is better if you'll go with this set. Still dont expect him much since it's not that good in terms of stats. It's a fighting type with low hp&defs and okay speed thus any super effective moves or some powerful STABs by faster opponents can 1H-KO him.