Simipour clearly has stiff competition when compared to the numerous other Water-types in UU. Luckily, it does stand out in a few areas: there's the obvious Nasty Plot (which it shares with no other Water-type bar Slowking), its good Speed stat that enables it to outspeed a lot of important Pokemon in UU, and its effective attacking movepool. Unfortunately, Simipour's frailty means even neutral attacks will take huge chunks of its HP, making switching in throughout the game a challenge, especially when you add Life Orb recoil and entry hazard damage to the equation. Generally, Simipour is a lesser option, but one would be mistaken to discount it as a threat.
Simipour's good Speed and usable Special Attack stat make boosting with Nasty Plot its most reliable option for sweeping. After a Nasty Plot boost, it can comfortably outspeed and OHKO many prominent Pokemon in UU, including but not limited to Hitmontop, Zapdos, Milotic, and certain variants of Mismagius. To put the icing on the cake, Simipour has access to Hydro Pump, which, after STAB, Life Orb, and a Nasty Plot boost, will do a heap of damage to most targets that doesn't resist it. Ice Beam and Grass Knot are used to cover Grass- and Water-type opponents, respectively.
For a more reliable option in terms of accuracy, Surf can be Simipour's main attack instead of Hydro Pump, but note it can sometimes fall short of several potential kills. For example, a neutral-natured 252 HP Uxie has a high chance of being OHKOed by Hydro Pump (94.0% - 111%), while Surf fails to OHKO without some prior damage (74.8% - 88.4%). The bottom line is this: your choice of a Water-type STAB move comes down to whether you favor reliability and are confident in your ability to provide entry hazard support, or prefer a more immediately powerful option at the cost of accuracy.Team Options & Additional Comments >>>
Looking at Simipour's stats, one would think it would make an equally good physical attacker. However, Hone Claws and Work Up, its two physical boosting moves, are not nearly as effective as Nasty Plot, and there are generally better physical Water-types available, such as Feraligatr, Azumarill, and Sharpedo. If you still want to run a physical set, Waterfall and Return alongside Low Kick (for Empoleon) provide great coverage. Likewise, a mixed set with Work Up is an option, but Simipour prefers investing all its EVs into one stat so it can hit as hard as possible. Taunt is a good move, but is similarly hard to fit on a set. Choice items could work on Simipour, but it's inadvisable for it to run sets that force it to switch constantly because of its general frailty.
Simipour's Dream World ability, Torrent, would be preferred over Gluttony in most cases considering Simipour finds itself with low HP quite often and the boost could be very helpful. However as it is only available from an event that released male Panpour, it is illegal with Nasty Plot, which is a breeding move. The stat boosting Berries also can work quite well on Simipour; Gluttony allows it to consume the Berries at 50% health, meaning you won't need to drop an attacking move for Substitute if you give it a Salac Berry. With a +1 Speed boost, only Pokemon with Speed boosts of their own will outspeed Simipour. Still, Life Orb will be missed for its ability to OHKO Suicune and Milotic after a Nasty Plot.
Checks and Counters
If Simipour manages to boost with Nasty Plot, few Pokemon can actually stop it from destroying the opposing team. Empoleon is a perfect counter since it's only neutral to Grass Knot, although it must watch out for Focus Blast. For a more offensive approach, the easiest way to beat Simipour is to revenge kill it with the long list of Pokemon that are faster than it and have a moderately powerful attack, common examples being Raikou and Choice Scarf Heracross. Finally, entry hazards and Life Orb wear down Simipour severely, so opponents can expect the water monkey to go down quickly if it is stalled out.