Accelgor

Accelgor looks like a tough, no-nonsense kind of Pokemon, but unfortunately its looks are arguably the only thing this Pokemon has going for it. Various other Pokemon boast superior stats and movesets, and Bug typing in the meta isn't particularly valuable either. A dex filler at best, with maybe hopes for a better future if given a stronger moveset. 

Best PvE Offensive Moveset

• Infestation is the best fast move available, and gets STAB.
• Acid is a poor move and lacks STAB. 
• Bug Buzz is superior to Signal Beam, though the difference isn't huge. 
• Focus Blast and Water Shuriken don't fit well here.
• Acid Spray is meant for PvP. 

Best PvE Defensive Moveset

• Water Shuriken is comparable to Infestation on defense and has counter-coverage against Rock and Fire Types, making it the best defensive move for Accelgor. 
• Infestation gets STAB and has better stats for defense than Acid.
• Bug Buzz hits harder than Signal Beam on defense, and the two have almost identical damage windows. 
• Focus Blast is too slow for defense.
• Acid Spray is meant for PvP. 

Infestation offers fast energy generation for Accelgor's slow charge moves, and benefits from STAB. Acid is a below average move for PvP. 

Signal Beam costs slightly less energy than Bug Buzz, which is significant enough due to the lack of a cheap charge move option energy-wise. Focus Blast is the only option available for coverage, and is quite valuable against the meta but demands a lot of energy. Acid Spray costs the least amount of energy, but is still moderately expensive, and doesn't deal much damage if unshielded.