The only problems I see:
While Blissey's only special weaknesses are Focus Blast and Aura Sphere (both practically non-existant, and the only one that will come with STAB is Aura Sphere Lucario), Togekiss has to deal with BoltBeam, omnipresent and way more common to get STAB.
While Blissey reaches 306 Sp. Def with a neutral nature and 0 EVs, Togekiss needs everything to reach 361, meaning SE Physical moves hurt a LOT.
Hold right there for a sec. As shown in the first post, a 255/255 Def Bold Blissey only beats Togekiss by 2 Defense Tiers in physical defenses. With 255 HP evs and 0 Def EVs, This Togekiss takes neutral physical hits better than 0/0 Garchomp (118.54) and is most comparable to 0/0 T-Tar (119.37). (and 0/0 Skarm as well... but who uses 0/0 skarm?) Granted, Garchomp and T-Tar are "sturdy enough" because if you don't kill them in one hit... they kill you. But these guys can take some abuse... as long as it isn't one of their 4x weaknesses...
From there, Super-Effective physical hits is a 7.27 penelty in the tier system, so Super-Effective hits like Ice Punch or Stone Edge will place Togekiss in tier 111... or about how Jolteon would take it.
This togekiss is no tank on the phsyical side. Standard Blissey beats this togekiss yet again here. But I wouldn't describe this amount of damage as "A LOT" as this Togekiss clearly takes hits better than say... a defensive Starmie.
For Reference... MixApe Close Combat or Flare Blitz with Life Orb deals 50.27% - 59.09%... making a 2-hit KO the majority of the time :-( (Just here because everyone seems to want this calculation)
While Blissey gets 600+ Hp with about half the maximum EVs in Hp, Togekiss needs ALL of them for a measly 374.
Yeah, 255/0 Blissey is like 5 defense tiers higher... Then again, Blissey is so absurd its crazy. It takes 255/255 for Regice to get to 0/0 Blissey's tier... ignoring its multiple weaknesses, few resistances and so forth. And Regice is the #3 statistical candidate in Sp. Walls, falling behind only to Chansey and Blissey. Aside from Regice, no other pokemon in the game can meet a 0/0 Blissey in Sp. Def... no matter how many EVs they put into HP and Def... although Shuckle, Basteodon and a few other rocks are exceptions because they gain an additional Sp. Def boost from Sandstorm boost. T-Tar just misses Blissey's tier by .03 points... only fractions of a percent worse than 0/0 Blissey in Sp. Def in a sandstorm with 255/255 Evs.... but I digress :-p
Blissey really is godly in terms of Special Walls.
Togekiss gets Nasty Plot, sexy Air Slash flinch, I get all that, but Blissey has Calm Mind and a 20% freeze/para hax, which is similarly efficient. I don't think making Togekiss a different Blissey is any better than making it a NastyPasser, WishSupporter, ParaFlincher, etc. Mainly because the ''different Blissey'' Togekiss is mostly different in only one thing: Being worse.
Well, the key difference is Nasty Plot on this Togekiss as well as a single STAB attack that is only 4x resisted by Rock/Steel and Magnezone. This is one step away from wall, one step closer to sweeping. Quite literally in every way actually. Togekiss is slightly faster than Blissey/Cresselia, and has significantly stronger Sp. Atk and Nasty Plot instead of Calm Mind to boost Sp. Atk.
Although, I've run ParaFlinch before... and I personally like this defensive set a bit better. Paralysis support seems like it has to come from someone other than Togekiss for it to work, because Togekiss just doesn't have as much defensive EVs as I'd like it to have. It needs to either have Paralysis suport prior to the event... or inflict it by itself.
And if they're slower than you already, Paralysis doesn't add too much. It turns their 40% chance of attacking into a 30% chance.
I love Togekiss, it's by far the best Normal/Flying type, one of the sexiest support pokémon, and the 60% Air Slash flinch is *really* annoying. I think gearing the nature and EVs to support his strenghts is far better than doing so to support his not-so-good abilities. I guess if you hate Blissey with that much a passion then you can find in Togekiss a halfway decent special ''wall'', but know that you'll be settling for mediocrity, plain and simple. Heck Togekiss doesn't even eat Draco Meteor better, because it lacks the threat of Ice Beaming the Dragon away. What are you gonna do to Salamence/Garchomp? Roost? Pray it's not mixed? Because if it is, the first Meteor + a strong physical move kills Togekiss.
Hmm... some fair points. Maybe the premature sucess in Shoddy is that most people are obsessed with using BL or UU pokemon in their teams, and obviously this Togekiss absolutely walls them. I guess more play testing with some full blown OU teams will change my opinion of it.
Well... at least it beats ChainChomp >.>