TRACE. Keep it, believe me. Check it:
Porygon2 @ Evolution Stone
Nature: Bold
Ability: Trace
EVs: 252 HP/ 96 Def/ 156 SpD/ 4 Spe
-Magic Coat
-Ice Beam
-Thunderbolt
-Recover
This is my anti-lead...it tears shit up. I know that seems so odd, but it alone has shut down teams magniificently. Max HP and balanced defences, except that SpD is one point higher, stopping Porygon-Z and Genosect from getting their Download boosts. Magic Coat is a giant middle finger to an abundance of leads. And that's not just because it's Magic Coat; people expect Pory2 to carry a status move, or TR, so it isn't uncommon to have Taunt thrown your way. Erufuun and Voltolos are no problem at all, AND you snag Mischievous Heart from them (priority Recover, woo!). Sableye is slower than Pory2 as well, so yay there. Oh, and Outrage from a +0 Ononokusu (yeah, I've seen it) 3HKOs this duck, while it 2HKOs back with Ice Beam. Thunderbolt is useful against DrizzleToed (and Magic Coat sends back Hypnosis), Gyarados, Starmie, Vaporeon, and Suicune. And Trace is a must, since it allows you to ability scout, something that's extremely important these days. Oh, and Tracing Swift Swin/Sand Throw is far from useless; you won't be faster than whoever you Traced it from, but you do have a chance of outspeeding their teammates with it.
I don't care about its tiering; Porygon2 is definitely a force to be reckoned with, if used well. Lol a ton of people ragequit against me yesterday after losing their strategies and half their Pokemon to the duck alone.