I am actually a big fan of using Samurott in RU, enjoying this set on a current team:
Samurott (F) @ Life Orb
EVs: 252 SAtk / 120 Atk / 132 Spd
- Hydro Pump
- Ice Beam
- Superpower / Grass Knot
The plan: spam Hydro Pump. Only 7 'mons in August's top 30 resist water, and everything else is so offensively oriented right now that it can't switch in. Max SpAtk for power, 132 Speed to outrun neutral base 55's (Crawdaunt, Bouf, Omastar), and rest dumped into Atk. Someone can probably tweak the spread to perfection to obtain a some extra HP EVs, but I opt to just use as much attack as possible since you never know what your opponent's Slowking spread is going to be (and let's be honest that's Samurott's big selling point)
Out of the aforementioned 7, I'd say only Lanturn and Feraligatr are consistently good switch ins.
The option of Superpower over Grass Knot just comes down to what you want to hit. Cryonogal and Clefable (as well as errant Munchlax) will take Hydro Pumps okay but fall to Superpower, but you need Grass Knot to prevent being walled by Poliwrath or Alomomola. The former two are more common, but pick your poison. Forgoing Ice Beam for Grass Knot is also an option since you have Megahorn to hit grass types, but you will then be in trouble against Druddigon and Tangrowth (though Tang can be 2hkod by Hydro).
He breaks walls down like woah, so most sweepers appreciate his assistance. Swellow and scarved Braviary deserve special mention for being able to take out Samurott's grass type nemeses, while also benefitting from Samurotts ability to break down rock and steel types. Rotom-C also is a standout mention for easily soaking up grass and electric attacks, as well as being able to provide Samurott with safe switch ins via Volt Switch.