Trace is the best ability for Porygon2 in my opinion. If you predict right you could end up with an awesome ability in most situations.
I would keep pain split on Cofagrigus instead of rest. I can't tell you how many times I've gotten in a situation where I have been able to use pain split with my Cofagrigus/Dusclops in red health.
You should consider stealth rocks on Swampert, idk if you are using this team on Showdown or in wifi battles but it is worth the trouble in getting it from a gen 5 move tutor.
You seem to have a lot of your IV spreads the same, max in an attacking stat and max in a defensive stat. I would suggest designating 3 for a core and 3 for attacking. In the core you would invest most of your IVs in defenses or hp, and your attackers would have max in a attack stat and max in speed.
If I was using that team my core would be: Cofagrigus, Porygon2, and Swampert, while my sweepers would be Togekiss, Medicham, and Arcanine.
