Thanks Shrang, changes made.
@ginga
Why do you bring up Scizor like that? Besides there being a 70% chance there will be no Scizor, Scizor isn't that hard to beat. Porygon-Z can take a Bullet Punch and OHKO back with some hazard support (although with Thunderbolt), but if Scizor switches in on the Thunderbolt you don't even have to worry about it (still with hazards). To your second point, most things need teammates to set up. Is SubDDnite bad because he needs phazers to be eliminated? Is BulkySD Scizor bad because he has problems with Magnezone? Not at all. Things need teammate support; no sweeper will ever be perfect to just send out and work. It doesn't need a terrible amount either, just a few hazards and you're good to go.
Don't quote percentages at me, I gave it a test run, and I happened to come across Scizor a lot, sure "you survive" but you are running Life Orb so you don't sweep either. Often, even with all the support I gave it, it would only get a 1 for 1 kill which just was not enough when I could be using something like Lucario (for example) which would do better with all the support I was giving it. You also need Thunderbolt to "beat" Scizor, + hazard support, and the QC team and I already stated that HP Fighting + Dark Pulse is usually better.
Sure, I know things need support, but you are clearly missing my point, its the amount of support it needs to function over other sweepers which makes it so hard to use. I am not alone in this, one QC user regarded it as "just so so borderline" (on whether to accept or reject) so I am not alone her in thoughts with Porygon-Z. Sub DD Nite doesn't really care about phasers btw, when it wins last pokemon (Perish Song Toed however, is more annoying) but Porygon-Z needs, hazards, a Download boost (which is really tricky to always pull off), and encore support, so it can set up with those shitty defences. Even when you set up, you are still royally screwed if they have something like Mach Punch Infernape (which I ran into), Conk, Scizor, CB Nite, SD Lucario which will all pick you off. in some cases, with just a tiny bit of residual damage. In addition, you are worthless against stall, and Balanced teams usually have shit like SDef Jirachi, SDef Tran (which will cripple you with paralysis or can phase you out) or something else I couldn't break though .
Porygon-Z was very much a 1 time thing, I needed to give it all this support for its one chance at sweeping, and if it failed cos it got phased out, then that was that, my chances at getting a second chance were practically zero.
tl:dr
It needs a fuckload of support, if you think its just a few hazards and you are good to go then, (putting it lightly) you are sadly mistaken.