Alright, I'll give a quick overview of it from a pair of fresh eyes because I know next to nothing about the making of this.
With a quick look over it's stats, I see decent HP, not so great attacking stats, good defense, very good special defense, and not so great speed. My mind immediately screams "WALL!" because of the defensive stats. However, looking at the ability, it becomes obvious that the main reason for this Pokemon is to counter weather.
Now, countering weather doesn't really work by stalling. The other weather user can easily switch out. That means it needs to have some way to put a heavy dent in weather users. A quick look at it's movepool reveals Focus Blast and Close Combat, which should both put a pretty heavy dent in Tyranitar, which it happens to barely outspeed also. However, due to Tyranitar's massive Special Defense during a sandstorm, Close Combat seems like it's a better option, but is unfortunately not exactly optimal because of the dreadful attack stat. I assume the people who made this aren't trolls though and that they gave Simishock just enough attack to OHKO Tyranitar. Another look at it's movepool reveals Thunderbolt and Volt Switch, with are both nice options for denting Politoed. Abomasnow should get taken down by a quick Focus Blast. Ninetails seems like more of an issue, so I'm not sure how well Simishock would counter Ninetails.
Anyway, right now we're looking at a mixed moveset, Close Combat to OHKO Tyranitar, Focus Blast for general STAB and killing Abomasnow, and Thunderbolt or Volt Switch, depending on the exact use you want for him, for Politoed. Simishock also has a decent support movepool in Circle Throw and Thunder Wave, but stalling seems very difficult without a reliable recovery move.
That's it for now, I'll come up with some actual movesets later.
