P2 doesn't like anything with toxic, or if it doesnt have shadow ball it lets aegislash and perish gengar do its thing. OHKO moves also really make the opponent think twice about playing the long game with P2. It also can't have foul play yet so if you have a setup sweeper take advantage of P2. To be fair alolan muk deals with a lot of other things too.
PZ doesn't really have counters once it sets up, so the goal is to prevent it from sweeping you on the setup turn. Make sure you don't kill an opponent's pokemon that lets PZ setup for free the following turn. You can disrupt it with encore, phase it out, speed control with rock tomb, or hit it hard during the setup so that scarfers like chomp and lele can outspeed the next turn and revenge kill it. Prio encore like whimsi can switch in on the setup turn and lock PZ into conversion unless the opponent counterteamed you and brought dark-conversion PZ. Muk can live a +1 adapta tbolt and clear smog the boosts away.
Cloyster struggles against a majority of steel types. Most aren't really counters after setup but they do usually win if they switch in on the setup turn. Bonus points for klefki for bringing the speed back to +0 thanks to priority twave and hitting a +2 attack -1 def with foul play. P2 is good against it too since tbolt isn't really an extra moveslot right now.
If your team struggles so hard against a mega scizor that you needed to pp stall with celesteela why not try putting flamethrower on it? Gyarados is also a pretty free switchin and can use scizor to start setting up dragon dances. It doesn't have superpower or knockoff until pokebank so aegislash is a hard counter right now too lol. Alolan marowak is pretty cool as well.
