[tehy]

I hate to recommend specially defensive hippowdon, but... well i love to recommend specially defensive hippowdon. Firstly, it's a great stealth rocker. It sucks that it can't quite wall tornadus-T, but if you make tentacruel max Spdef, it can definitely deal with tornadus-T well, with chansey chipping in. It can't quite wall off dragons, but it actually makes an alright check to them. And of course, it gives you weather control, which is always nice. It also gives you a way to deal with SDcario, but you'll need to give it more phys.def evs than it has currently. TBH, i'm not sure why you need max def. tentacruel- it's not like you need to spin a lot, what with xatu and all, atlhough i suppose fire-types can get annyoing. Basically, Spdef hippowdon gives you weather control, and a pretty sweet mixed-wall. Hey threat list, hippowdon says hello!

Jirachi – Specifically Calm Mind just loses to Spdef hippowdon

Latias – The issue here stems from most stall pokemon being a little screwed against him in any case, so i can't help with that. But he can still reliably phaze HP fire cm latias.
Reuniclus – Fuck. I agree. Same as above. BTW, i use sableye to deal with both of these, and even though you can't fit him (maybe for xatu?), it would be an interesting idea to think him over.

Thundurus-T – Nasty Plot is hell to deal with and Amoonguss and Chansey are my best shot. Any other set is easily dealt with.
Switches in on t-bolt;roars no matter what. Can't really help with that.

Toxicroak – An odd thing to be weak to because SS kills his healing and he takes EQ to the face

Victini – I found out the hard way that Victini just ruins this team. Hippowdon can take a hit and EQ but that's about it.

Volcarona – Far and away my most medium weakness. Hippowdon gets up SR almost always, then phases him basically no matter what at full health. People are running giga drain more, but t-spikes helps here.

So as you can see a lot of threats are now more like setup bait, and others are more manageable. With SS and SR, physical dragons like nite and mence are much more manageable-dragonite can be phazed once by hippo, and once by skarm, which means that by the time it comes back in it's nearly dead from 3 SR and SS in general. Salamence is more of a problem, but he's usually used as a scarfer and spdef hippowdon actually walls him, especially if you give him enough defense for SDcario w/LO.

Edit: Here's an idea:Put toxic on something. that way, you can confuse ray latias with xatu, then u-turn (Not sure if it breaks sub), then hope it hits itself in confusion as you toxic. I find that toxic on amoonguss is bomb over HP ice, and that also helps with speed creep.

Cm latias doesn't really run max def, but... why not just run perish song Spdef celebi? U-turn/giga drain/perish song/recover.

Super edit: Yeah, i had to go, but i think we all know how perish song celebi rolls, i don't feel like overly explaining. Celebi's also nice against toxi, the BU variant. But here's an idea-sub out bronzong for Shucatran with just enough bulk to survive +1 EQ's from nite/mence after sr, and enough SPatk to KO with hp ice. Hp ice/earth power/stealth rock/lava plume or fire blast. MINDBLOWN!
Shuca is better than balloon for stall IMO because it's not burned with every hit, but only when hit by earth moves, so you can lure them in and hit them, instead of forcing them out and having it popped later. Besides, i thought the whole point of phys. def tentacruel was just to have something for victini-what gives? Consider swapping him out for some form of starmie. No tspikes sucks, but starmie can take one (1) hit and counter back, as well as semi-sweeping lategame. And it spins much more reliably. (Also consider max phys. def donphan? With SR so zong can have another move like TOXIC which with gyro ball can get subCM latias TOXIC'd? ON A ROLL.)