Bibarel

Bibarel is often regarded as a meme, without any meaningful use in the meta. Various Pokemon flex superior stats over this goofy-looking Pokemon, and on defense a weakness to Fighting-type attacks is generally not favorable when considering some of the best gym defenders share that weakness. 

Best PvE Offensive Moveset

• Water Gun performs better on offense, and actually has a use in PvE.
• Take Down gets STAB, but can't be Super Effective against anything, making it useless.
• Surf enables Bibarel to fulfill a Water-type role.
• Hyper Fang isn't a terrible move, but lacking a Super Effective multiplier is painful. 
• Hyper Beam and Rollout have no use. 

Best PvE Defensive Moveset

• Rollout is generally better for defense due to stronger stats and good coverage.

• Water Gun and Take Down fall behind by a fair bit.
• Hyper Fang hits harder on defense, and provides neutral coverage at best.
• Surf isn't far behind in defensive performance, but Grass-type attackers laugh at it. 
• Hyper Beam is too slow for defense. 

Water Gun provides decent damage and energy gain. Take Down is one of the worst fast moves in the game. 

Surf (65 power/40 energy) and Hyper Fang (80 power/50 energy) provide great neutral coverage and good shield pressure. Hyper Beam is way too expensive to be useful.