Volbeat

This is a dex filler, and nothing more. Ignore Volbeat and focus on more important bugs.

Best PvE Offensive Moveset

• Struggle Bug and Bug Buzz is definitely the way to go, all other options are sub-par.

Best PvE Defensive Moveset

• Struggle Bug and Thunderbolt is the best option on defense.
• Tackle is pretty weak on Defense, while Bug Buzz shares typing with Struggle Bug, making it less reliable for defense.
• Signal Beam comes out slightly before Bug Buzz, but the difference is miniscule while the damage loss is significant. 

Tackle is pretty average, while Bug Buzz has decent power and Thunderbolt is for coverage.