Slowbro

Slowbro is a likely overlooked Pokemon in your collection, but don't count it out. It has access to one of the best defensive fast moves in the game, Confusion, as well as good charge moves for defense. These are complemented by respectable bulk. Throwing this 'mon into a gym will get you some staying power. Its resistances make it a great counter to many common gym attackers, as does its great charge move coverage options.

Best PvE Offensive Moveset

• Confusion is generally superior to Water Gun; both are usable on offense but the former wields higher DPS and more meta relevance.
• Surf pairs well with Water Gun to make Slowbro a Water attacker.
• Psychic pairs well with Confusion.
• Ice Beam, Scald, and Water Pulse aren’t very useful for an offensive Slowbro.  

Best PvE Defensive Moveset

• Confusion is distinctly superior to Water Gun due to the massive power difference.
• Scald is the best Water Type Charged Move option on defense
• Surf is a 2-bar move with a fairly early damage window
• Ice Beam and Psychic have similar performance overall, though Ice Beam is preferred due to counter-coverage and being off-type with Confusion.
• Water Pulse is just inferior to Surf

Confusion is generally more preferable as it deals more damage than Water Gun. However, Water Gun's much shorter duration and different coverage can be useful sometimes

Surf is necessary due to its cheap cost, as Slowbro's other moves are expensive. Ice Beam is often the preferred second Charged Attack due to its wide coverage, nailing pesky Dragon-, Flying-, and Grass-type Pokemon. Psychic is a good STAB move but its coverage may be redundant with the heavy Psychic-type damage from Confusion. Water Pulse is terrible.