Just my luck, the one time I decide to take another peek at Smogon, there is a Porygon2 thread up and running.
I just have to get a few words in edgewise.
-Porygon2 is not and never will be a reliable counter to Salamence. Two hits from Draco Meteor from even weaker variants will take down Porygon2 regardless of your EV investment. Not to mention a +1 LO Outrage almost guaranteed OHKOs P2, so even against physical Salamence, you're fucked.
-Porygon2 can't handle Salamence, Lucario, Scizor, or any of the popular sweepers anymore. What it can do, is cover some of the more obscure weaknesses your team has. I used to shoehorn in Porygon2 into my teams because it does a damn good job at covering things you've forgotten. Your opponent sends in generic sweeper X, but your team is so overspecialized against the top 10 threats, you don't have anything on it. Enter Porygon2. He takes a big hit, but paralyzes the sweeper, and easily recovers it off later. Porygon2 isn't "the best" at anything (except stopping gyarados) but it's "good enough" to get you out of those difficult situations.
-All that gravity and trick room bullshit is a waste of time. If you're using Porygon2, you need Recover, then you need Thunderbolt and Ice Beam. That's three slots gone, and the last one should be a move to deter things that unSTABed boltbeam can't... say Toxic, Thunder Wave, or maybe HP Ground for heatran and magnezone. Steer clear of gimmicks, trust me. It's only a surprise the first time, and basing your team on surprises is risky at it's best.
TL;DR, Porygon2 is like carrying a paperclip in your pocket. Most days, it won't be of any use to you, but maybe someday it will save your ass and you'll be glad you hung onto it.
Oh, and hi Chris, I see you're still a badge-less nobody. I'm sure ripping on users past will make everyone notice you.