Well, everyone seems to try and avoid the belief bandwagon by hopping on the disbelief bandwagon. I prupose middle ground!
Yes, this deck is bad. Very bad. As of now, it is listed with sevral cards as techs that don't allow you any bench space. So let's breka a few parts off. Shiftry isn't the greatest card, Claydol/Uxie are gods, mesprit is one of the best cards in the format and Giratina is too big a risk, and too much a hassle. Dugtrio is a triple serving of potion weak idiocracy screaming for Dusknoir to Dark Palm his buddy Claydol.
So let's take the good from the bad:
Good:
Shiftry
uxie/Claydol
Mesprit
Shiftry with early mesprit Lock is more then viable. it's good. Shiftry can it for an easy 40-60, seedot prevents most forms of donk, and Mesprit gives you time to actually set-up. Now, you should pakc this deck full of SSUs and TSDs. Not just to get back mesprits for consistant power lock, but also to make fun of your opponent. Make sure that smile is EXTRA big as you say, "I'll play SSU. Oh and i actually GET to flip!" Now all you need is a way to not rely on Mesprit fully, and get around Dialga. Palkia Lv.X, Luxray GL Lv.X or Poke Blower. Pull up a Claydol you've power locked or a Dailga G Lv.X who's giving you trouble, and shut'em off1 Your opponenet can't SSU Claydol, so hah! PokeTurn would be annoying, but they only get to use it 4 times. If you play this deck well, they should either be confused or knocked out every turn.
And let's not forget, this deck gets to play Lookers! you have to keep your hand near the same size as your opponents, and between Claydol and lookers, that shouldn't be a problem. So now, Shiftry doesn't even have a beedrill autoloss! Sure it might not be the best deck, and some would say it is a weaker version of Psychic Lock, but, consider the following:
Shiftry is a dark type: It is not resisted by Dialga or Magnezone
Shiftry is resistant to psychic: Psychic Lock does 40, Gengar can't hit for jank, and can't be hit for 50 by Azelfs and Uxies.
Shiftry doesn't have a power: While gardevoir's set-up power is amazing, it is also a 2HKO for Gengar. They level up, Gengar drops a bat, and still has a 2HKO.
Shiftry is most certainly a dark type: Gengar and Dusknori suffer a +30 weakness.
Shiftry can shut off bodies: Amphy lock, Shaymin (that'd be a fun body to lock
), Dialga G Lv.X etc suffer hard here.
Shiftry has
gas Wind: No TSD, SSUs, Discharges etc will do anything agaisnt this fool!
Shiftry is still a dark type: Its small damage output can be increased with Special Darks!
Shiftry has 1 Retreat Cost and two attacks1