Though Bisharp has superior Attack and a better typing, Obstagoon is the better choice in-game. This is because it can be caught first and it evolves much earlier (Level 35 compared to Level 52!). This means you'll get Obstagoon around the 5th Gym in terms of progression, whereas Bisharp has to wait until after the 8th Gym.
Additionally, Obstagoon has better HP, Defense, and Speed than Bisharp, compensating for its lower Attack stat. Its movepool is varied enough to be effective throughout the game and it only really struggles with a few battles like Opal and Bede. Though both Pokemon will work for the endgame, Obstagoon is more consistent and more powerful for the majority of a playthrough.
Obstagoon's main flaw is its poor level-up movepool and you'll need to dip into TMs and TRs to flesh it out. This can take time if you don't like hunting for them, but its capabilities are significantly hindered without the support.
Obstagoon
Ability: Guts
- Throat Chop (TR) / Night Slash (Move Reminder)
- Facade (TM in Motostoke Riverbank) / Headbutt (Level 12)
- Cross Poison (TM in the Dusty Bowl)
- X-Scissor (TR) / Seed Bomb (TR) / Hone Claws (Level 15)
