Yeah, Machoke has better physical bulkyness and slighty better special bulkyness, but the loss of 30 Attack BP and no-item is very disappointing. Machamp Lead works due to Lum Berry, and most of other sets love Lefties.
Well I said that I would NOT choose Machoke anyway, as loosing those 30 points in attacks is too big difference to seriously consider it. However as a defensive RestTalker Machoke may work even in OU - it has bulk and fortunately recovery for this. Invest enough defense to always survive two CB Earthquakes from Tyranitar, rest invest into Attack. Machamp must invest a really massive number of EVs to secure surviving here.
Slowpoke Stoned 252 PV/252 Def Nature + againt a Slowbro with the same spread.
Well, I never considered Slowpoke, as I saw difference in statistics between them. However I see some little use of it in future NU (or something similar). With so many Fighting types this Gen, some older ones may end in lower tiers like Primeape, Hitmonchan, Machoke, etc. giving Slowpoke quite good niche.
The assets are very slight, especially with Lefties, but Tangela has a more reliable Leech Seed...
Honestly I don't think it's worth it, especially when Tangrowth goes with special defensive route. However in physical it may be considered... but I would still choose Tangrowth, just for Leftovers and having similar bulk to even boosted Tangela.
I guess, you are missing out someone, guys. What about Piloswine? I just noticed, it would become incredibly bulky. Its typing actually really sucks defensively + it is really slow, but mentioning the negative aspects - that's it. I'll come up with some essential advantages:
1.) Not affected by hail
2.) Not affected by sandstorm
I think I would go a bit different route. Thanks to Thick Fat it doesn't die from random Fire Blasts from Salamence and Sazando. There may be way to play it - investing in special bulk, as you take 47.03% -> 55.69% from Life Orb Neutral Salamence's Draco Meteor and just Ice Shard it back, while easily surviving unboosted Life Orb Outrage
(and Choice Band hit), if you mispredict. It looks extremely similar with Dragonite and Flygon. Heck, you take Draco Meteor from MixQuaza (58.91% --> 69.80%) with Max HP/Max SpD Neutral Piloswine (in other words you may use Adamant) and Ice Shard it back. If you face DD or SD, the worst what may happen it to take 54.95% --> 64.85% with Max HP from Adamant SD Life Orb E-Speed and again Ice Shard is here for OHKO. Heck, the funniest thing is that you take 71.29% -> 84.16% from Adamant Choice Band Outrage Rayquaza, so Stoned Piloswine is 100% check against Rayquaza, lol. This Piloswine beats EVERY single x4 weak Dragon in game. However against Sazando and other no x4 weak ice Dragon Pokemon go with something else - it doesn't have enough power.