Cool team. I like how you've used a few original pokemon, the ones less seen in NU. I have a few improvements, though, that will definitely help it win more battles.
Persian
Looks awesome. I love this guy, he's like a mini Ambipom :') I would give him a Jolly nature though, as otherwise he's at risk of being outsped by threats like Cincinno.
Haunter
Nice. For Substitute + 3 attacks though, Life Orb wears you down all too quickly. Black Sludge and Expert Belt both make good replacements for that. Also, Thunderbolt and Giga Drain don't give you the best coverage, and allow Skuntank to walk all over you. Shadow Ball, Sludge Bomb and Hidden Power [Ground] are the better choices.
Skuntank
Skuntank looks great, I like what you did with Substitute, but you know, Taunt is always an option.
Ludicolo
Ludicolo! :] One of my faves, although I believe it makes your team LU (RU) on PO, which would be why you've come up against Tangrowth so much. The set looks great, although Giga Drain gives you nice healing, and also gets better coverage with Ice Beam. That's why I run it over Scald.
Gardevoir
Man, Gardevoir is great. Don't know why people don't use it more often. Anyway, this looks like a really good team supporting set, except for one thing - it doesn't have Will-O-Wisp! It's great on her (him? lol) to patch up her weaker defense, and also provide passive damage. Replace Thunder Wave for it. Surprisingly, base 80 speed is really not bad in NU, much much better than Musharna and the like.
Sawk
Lmao. I know Sawk's movepool isn't exactly overflowing with options, but Toxic? On a scarf set? I know Smogon suggest it, but that was before BW2's move tutor additions. He now gets the ever so helpful elemental punches. Plus, Mold Breaker is awesome for him, especially as your team doesn't have a spinner. I'd go with Close Combat, Ice Punch, Earthquake, and Stone Edge/Payback/ThunderPunch/some other filler move.
Well that's me done, hope I helped :]