Punchshroom
FISHIOUS REND MEGA SHARPEDO
Thunderbolt has the merit of hitting Tentacool and opposing Skrelp.Squabbling aside, Skrelp is pretty cool. It's both strong and bulky, which means it'll definitely have a niche in LC. On top of that, it has room on its sets to run Toxic Spikes without having to sacrifice a precious moveslot because Water/Poison has really good coverage. This allows you to run something like Toxic Spikes / Water STAB / Sludge Bomb / coverage move of choice or additional Water STAB. With that last slot, Shadow Ball is probably better neutrally than Thunderbolt, as it allows you to nail Frillish as well as hit Ferroseed neutrally if you ever find yourself needing to finish it off. Thunderbolt would be nice for bulky Water-types, but I'm sure Adaptability Sludge Bomb does a good number to Staryu, and you can't hit Chinchou with Thunderbolt anyways.