This is a very very derpish fish... kinda like the Stunfisk of the 3rd gen...
Physical-cash
Item: Choice Band
Nature: Adamant
Ability: Hydration/Anticipation
Moves:
Aqua Tail/Waterfall
Earthquake
Spark/Zen Headbutt/Stone Edge/Thrash/Flail
Spark/Zen Headbutt/Stone Edge/Thrash/Flail
Ok, the trick here is just smoosh them, he really doesn't have the speed to pull this set off, but he has a very physically orientated move-pool.
Aqua tail for power, Waterfall for flinch and accuracy
Earthquake smooches
Spark gets waters and flyers, zen headbutt gets fight poison types, stone edge gets flying types, fire types and Ice types, and it has more power etc, but lower accuracy.
Thrash has a high power, especially with the choice band boost, and flail is good if you have little faith in your derp fish.
with this set you could replace a move with dragon dance, and then use life orb or something similar as an Item.
EV's: 252 Atk, 252 spd, 4 whichever defence.
Special-Cash
Item: Choice Specs
Nature: Modest
Ability: Hydration/Anticipation
Moves:
Surf/Scald/Hydro Pump
Earth Power
Ice beam
Future Sight
Surf has power and accuracy, scald has a nice burn chance Hydro pump is powerfull, but in-accurate, up to you.
Earthpower is the special answer to earthquake, and has a nice little chance of lowering the foe's special defence.
Ice beam deals with the only type this guy has a problem with, the grass type, and it has a nice range of coverage.
Future sight, because there was nothing left to fill this space, and i know it's not good on this set, but the only other special moves left of note were Hyper beam, hidden power and round, and because i know nothing about hidden power mechanics i chose that.
EV's 252 Sp Atk, 252 Spd, 4 whichever defence.
Mix-cash
Item: Choice Scarf
Nature: Hasty
Ability: Hydration/anticipation
Moves:
Surf/Aqua Tail/ Waterfall/Scald
Earthquake/Earth Power
Ice Beam
Zen Headbutt/Spark/Stone Edge/Thrash/Flail
Basically this set is to catch your opponent off guard, so they think you have either a choice band/specs set, then you switch in and BOOM.
Just see above for what you want to choose.
EV's: 252 Spd, 128 Atk, 128 SpAtk
Slippery Fish
Item: Leftovers
Nature: Sassy/Relaxed
Ability: Hydration
Moves:
Rest
Substitute
Toxic/Scald/Swagger
Surf/Waterfall/Earthquake/Ice Beam
The idea for this set is to survive for as long as possible.
Rest works FANTASTICALLY well with hydration, substitute works well with his High Hp.
Toxic poisons-standard. Scald is nice because of the burn, or you could choose swagger if you're feeling particularly Haxey
Last move is to stop you being taunt bait.
derp features...
Item: Leftovers
Nature: Jolly
Ability: Hydration
Moves:
Dragon Dance/Amnesia/Tickle
Dragon Dance/Amnesia/Tickle
Rest
Earthquake/Waterfall/Aquatail/Stone Edge
The idea here is to boost your attack and speed then SWEEP, or you could reduce the opponent's stats and let another team mate come in and smoosh, or you could boost your special defence and lower their attack.
Then you recover any lost health
and the last move is to stop you being taunt bait.
EV's 252 Speed, 252 Hp, 4 Def
just flailing around
Item: Custap Berry
Nature: Adamant
Ability: Anticipation
Moves:
Endure
Flail
Protect
Filler
The concept is simple endure, then flail.
Custap gives you priority in a pinch, so you cen definately launch a 100% power flail.
protect is for after the custap, and you sense a move a-coming
The filler can be anything... i mean after the custap is gone you're pretty much doomed, many MANY things are faster than whiscash... you could try substitute but meh...
EV's 252 Atk, 252 Spd, 4 Hp.
sorry it's been a long one, but i saw his moveset and was inspired :L