Electrolyte
Wouldn't Wanna Know
But with setting up comes vulnerability to taunt and encore and perish song. I'm not saying that all pokemon should just ditch their set up sets and go for choice, I'm saying COULD all offensive pokemon USE choice items effectively. You're right, many of them depend on setting up to sweep- so pokemon like Cloyster or Volcorona are out of the picture.
If you think about it, it's really hard to counter choiced pokemon- many people resort to sacrificing and revenge killing later. However, some choiced users, such as Scizor or Mamoswine or CB Techniloom, can revenge revengers, thus ending the revenging of the opponent, opening up sweeps for other choiced pokemon. Walls won't work as well because now many of the pokemon in your team are stronger than the walls usually deal with, in fact 1.5x stronger, which means many just-good-enough walls will no longer be useful. Stall goes down too, because with choiced scarfers to outspeed yet still deal massive amounts of damage, already rare stall pokemon such as stall gliscor or toxic blissey will also go down. Don't forget about Trick, as it completely shuts down most walls that choiced teams have trouble facing. As for hazards, there is Specd Starmie to spin (though I don't recommend using it just for that purpose) and Specd Espeon to reflect (both sets are very rare however).
If you think about it, it's really hard to counter choiced pokemon- many people resort to sacrificing and revenge killing later. However, some choiced users, such as Scizor or Mamoswine or CB Techniloom, can revenge revengers, thus ending the revenging of the opponent, opening up sweeps for other choiced pokemon. Walls won't work as well because now many of the pokemon in your team are stronger than the walls usually deal with, in fact 1.5x stronger, which means many just-good-enough walls will no longer be useful. Stall goes down too, because with choiced scarfers to outspeed yet still deal massive amounts of damage, already rare stall pokemon such as stall gliscor or toxic blissey will also go down. Don't forget about Trick, as it completely shuts down most walls that choiced teams have trouble facing. As for hazards, there is Specd Starmie to spin (though I don't recommend using it just for that purpose) and Specd Espeon to reflect (both sets are very rare however).