which of the following is a better wall? for UU and OU enviroment? i want the one that can perform well in both. mainly for defense but overall for both special defense and defense. lets assume the IVs are 0 across the board

Torterra 252hp 148d 108a item:(help me out here =D)
stone edge, earthquake, curse/stealth rock/light screen, leech seed
**the light screen is to help mitigate ice beams

OR

Slowbro 252hp 212d 44sa item: leftovers
slack off, calm mind, surf, ice beam/psychic

OR

Slowbro 212hp 252d 44sa item: leftovers
slack off, surf, ice beam/psychic, thunder wave/yawn

I vote the 1st slowbro set. I can't see torterra working as a good wall in general, maybe a rest talker will do, but a 4x ice weakness is too easy to exploit.

For the slowbro go with ice beam in the last slot, as you can CM stall most other waters that resist water/ice. Beware of toxic though.

I vote against using Torterra he is too slow to put up a Light Screen to reduce special based damage when Ice Beam will OHKO him anyway.

I would use the first Slowbro set. As MasterChef said use Ice Beam on the last, and use Calm Mind to stall out the opponent and be wary of Toxic.

i hate to be a noob but why would toxic be a problem so much?

Because with toxic poison the damage increases each turn. So within a few turns the damage will do too much for you to stall behind, even with slack off.

Plus the only way to rid yourself of Toxic Poison is to use Rest. You could give them both Sleep Talk to go along with Rest, but then again there are other much better Sleep Talkers in the UU game namely Milotic. But I'm not saying they aren't that bad of Sleep Talkers you can give Torterra Rest, Sleep Talk, Earthquake, and Stone Edge for the good ole Ground Rock combo which is only resisted by a few Pokemon plus Torterra has enough bulk to pull of a Rest. But then again Milotic is a much better Sleep Talker than either of them could hope to be.