Blissey is indeed, the best special wall in the game in terms of defense. Calm proves to be better than Bold these days with the increased power of most special attackers. Bold Bliss just can't cut it well anymore.
Blissey@Leftovers *(Insert fat Blissey joke or line here)*
Calm, Natural Cure
252def/216sp.def/40 HP (or 40sp.atk)
Seismic Toss
Softboiled
Aromatherapy (or Heal Bell)/Ice Beam
Thunder Wave/Toxic/Ice Beam
The last options are team support: Ice Beam makes sure Gengar doesn't 100% stall you in return (and if it's the sub-puncher, you're in trouble without the Ice Beam.
OR
Wish
Protect
Seismic Toss
Thunder Wave/Toxic/Ice Beam
WishBliss is very good team support, but banned on some shoddy servers for some stupid reasons.
Kuggles gets +5 awesome for Pory2.
Porygon2@Leftovers/Lum Berry *Upgrade ME A-hole!*
Modest, Trace (Trace is required)
240HP/164Def/12Sp.atk/92Sp.def
Ice Beam
Discharge/Thunderbolt
Magic Coat/Thunder Wave
Recover
Use this as a lead. It's a wonderful Gyarados/Physical Salamence counter, Tracing their Intimidates back at them. With Lum Berry, you can afford to use an attacking move against Gengar cure the sleep, then Magic Coat the same anticipated Hypnosis next turn. Recover any damage received, for Pory2 is a very sturdy Pokemon.
As for UU, Probopass enjoys a support Pokemon, such as Xatu, which covers its weaknesses well.
Probopass@Leftovers
Calm, Magnet Pull
252HP/168sp.def/88spd
Stealth Rock
Thunder Wave/Toxic
Earth Power
HP Rock/Flash Cannon
Probopass is a very sturdy Pokemon, hindered really, only by its two weak spots, fighting and ground. You can use Magnet Rise to lose your ground weakness and make an immunity if you'd like, which at that point, you can become a steel killer with proper EV changes. Anyway, bring Probopass in on a Choice Banded Pokemon like Scyther (bar Brick Break), and set up as wanted. HP Rock vs. Flash Cannon is basically coverage issues, as both receive STAB. Earth Power is just awesome in general and destroys steels, which these EVs allow you to outrun standard Aggron. (I'm pretty sure at least...)
If you want more offensive sets, let me know.