While Simipour has good coverage and excellent speed, there's a mon that outclass Simipour as a Water late game cleaner in PU and NU, and it should do the same in RU
Floatzel @ Life Orb / Specs
Ability: Water Veil
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Hydro Pump
- Ice Beam
- Focus Blast
- Baton Pass
With a less amount of Sp Att. (same than Blastoise) and lack of Grass Knot, Floatzel still seems to be a better option thanks to its higher speed which allows to outspeed Delphox and
Virizion which is huge, + speed tie with Sneasel (and Ambigod+Flinchcinno). The lack of strong move to lure down bulky water is compensated by accessing to Baton Pass, which allows a clean switch-in for Mons like Virizion or Venusaur to come free on a bulky water/grass to check Floatzel. It's coverage pressures most rocks resist the way it can paired up with Tyrantrum as well, getting synergy with most biggest threads in RU. It's physical set is not that powerful but it get access to a fast STAB Aqua Jet to revenge kill Fletch, which is quite valuable to Offense builds.
Simipour gets access to great set-up as well as better movepool (Bulk Up Float is a thing on lower tiers though), but as a cleaner Floatzel speed makes it much valuable.Plus, mons like Hoopa are much better setting up NP thanks to higher bulk and attack stats, outclassing Simipour on this way which needs lots of support for getting a spot to set-up. Floatzel offers better utility on BP, Taunt, Pursuit or Switcheroo as well, so if any Water cleaner can get to be ranked, then it should be Floatzel.
Damage comparission:
252 SpA Life Orb Floatzel Ice Beam vs. 0 HP / 4 SpD Venusaur: 190-226 (63.1 - 75%) -- guaranteed 2HKO after Stealth Rock
252 SpA Life Orb Simipour Ice Beam vs. 0 HP / 4 SpD Venusaur: 211-250 (70 - 83%) -- guaranteed 2HKO after Stealth Rock
Crappy replays (I've been tired of mons lately but Floatzel still do things)
http://replay.pokemonshowdown.com/rususpecttest-354728357
http://replay.pokemonshowdown.com/ru-356895060
TL;DR:Floatzel outspeeds Virizion
Regarding the matters that Floatzel outclasses Simipour, I dont quite agree.
While Floatzel might be the better late-game cleaner in PU and NU, Im not sure that transfers over to RU, as the only pokemon that Floatzels is guaranteed to outspeed in RU that Simipour doesnt, are Delphox and Virizion. I can see outspeeding Delphox being an advantage, as Floatzel OHKO-es it easily, but the same cant be said for Virizion:
252 SpA Life Orb Floatzel Ice Beam vs. 0 HP / 0 SpD Virizion: 156-185 (48.2 - 57.2%) -- 91.4% chance to 2HKO
252 SpA Choice Specs Floatzel Ice Beam vs. 0 HP / 0 SpD Virizion: 178-210 (55.1 - 65%) -- guaranteed 2HKO
Unlike Venusaur, which only needs to have taken 1 or 2 rounds of stealth rocks + 1 round of recoil from Life Orb to be knocked out by Simipours/Floatzels Ice beam, Virizion needs alot more prior damage to be knocked out by Floatzel, as Virizion is resistant to stealth rocks, and takes much less damage from Ice Beam than Venusaur does.
Of course, Simipour cant take down Virizion at all, but I got the impression that the main reason for why Floatzel outclasses Simipour is that it outspeeds Virizion, and as implicated above, this doesnt seem to be too much of an advantage.
And then there is the advantages Simipour has over Floatzel which, as being mentioned, is the higher power and access to Grass Knot. While the two water types come close in power, as you showed with the Venusaur calcs, the difference in power might still be a factor that changes the tide in a battle.
252 SpA Life Orb Simipour Ice Beam vs. 4 HP / 0 SpD Sigilyph: 252-299 (88.1 - 104.5%) -- 31.3% chance to OHKO
252 SpA Life Orb Floatzel Ice Beam vs. 4 HP / 0 SpD Sigilyph: 231-273 (80.7 - 95.4%) -- guaranteed 2HKO
252 SpA Life Orb Simipour Hydro Pump vs. 0 HP / 0 SpD Medicham: 243-289 (93.1 - 110.7%) -- 93.8% chance to OHKO after Stealth Rock
252 SpA Life Orb Floatzel Hydro Pump vs. 0 HP / 0 SpD Medicham: 222-263 (85 - 100.7%) -- 43.8% chance to OHKO after Stealth Rock
And the lack of Grass Knot is also an issue, as shown in your first replay, where Floatzel baton passes out to Flygon on the Seismitoad, where Simipour just could have KO-ed it or forced it out.(Floatzel could have had HP grass, but it still doesnt OHKO with life orb).
And the fact the Simipour can 2hko Blastoise, Slowking and Jellicent, while Floatzel has to hope for the 3hko on those,(assuming it is Life Orb) is also something to take into consideration. Yes, baton passing into Venusaur is an option, but that allows the opposing pokemon to do what they please for that round, as well as eventually burn the Venusaur on the switch in.
But I would like to point out that Floatzels Water Veil ability can be rather useful, especially if you use taunt together with it, as it allows it to completely shut down Alomomola. So there is a niche that Floatzel can have, but it might not be the best idea in conjunction with an all out offensive set.
All in all, I dont think Floatzel should be taking Simipours slot as a fast, offensive water type, due to its advantages in speed over Simipour might just be as important as the advantages Simipour has with its higher damage-output.