Choice Specs Tri Attack is setup-fodder for Mismagius and Rotom. And Choice Band Spiritomb can nail it with Pursuit on the switch. At that point, it is easy picking for anything with a priority move. And without a Scarf, it can be revenge killed easily. Swellow always OHKOs with Guts-boosted Facade. Unboosted Psychic from Timid Alakazam does over 80%. Jolly Scyther's unboosted Aerial Ace does over 70%, while Brick Break does over 80%. The Morning Glory Arcanine set always OHKOs with Flare Blitz. Unboosted Timid Houndoom's Fire Blast always OHKOs after Stealth Rock damage. Choice Scarf Hitmonlee's Close Combat absolutely annihilates it, and Band Hitmonlee's Mach Punch will usually OHKO after Stealth Rock. Technitop's Mach Punch will OHKO more often than not, and always will after Stealth Rock or Fake Out. Absol's Sucker Punch does over 70%. Specs Tri Attack can only 3HKO Aggron, while Head Smash obliterates Porygon-Z. Registeel is 3HKO-4HKO'd and can set up Stealth Rock, Thunder Wave, or Explode back. So, as you can see, Specs Porygon-Z is not as broken as it seems.