Despite coming later than Liepard, Bisharp is the superior choice. Bisharp has higher Attack (125 vs 88), a better movepool, and a stronger typing (even with the 4x Fighting weakness). Bisharp's main problem is its high evolution level: Level 52 means you'll be using Pawniard until after the 8th Gym. For this reason, I don't actually recommend using either — Scrafty and Grimmsnarl are both more efficient Dark types.
If you still choose to use Bisharp despite its levelling problems, it functions well as a physical attacker.
Bisharp
Ability: Defiant
- Iron Head (Level 57)
- Night Slash (Level 40)
- Brick Break (TM on Route 8)
- X-Scissor (TR) / Poison Jab (TR) / Slash (Level 35)