Pokemon is all about percentages, so the absolute stat difference doesn't count for much. The Defense difference between Bold and Calm on max Defense Chansey is ~9.17%, but that's still not far off the maximum 10%.Hrm.. In any instance is it really worth using a +Def Nature on Chansey? With 252 Ev's she hits 109 Defense and the bold nature tacks on additional 10 def. Not really worth it.. I think. Opinions?
There seems to be a misconception, Chansey CAN take some physical hits from medium power pokemon, such as an Earthquake from Steelix.im using calm + 252 hp / 252 spD because walling raikou and magneton and other big special sweepers is a lot more important to me than not being ohkoed by a physical attack. Chansey will rarely take physical attacks anyway and if she does take one, she would most likely die anyway :/
This is likely the case for a great many of the pokemon now in Smogon's UU, since the "drop everything and make a UU NOT based on old standards" is a historical first for pokemon. I mean, I don't think Arcanine, Blaziken, Rhydon and Raikou ever expected to find themselves in UU.Also, random thing, UU is the lowest tier Chansey has ever been in! It was OU in RBY (back in the days when it had a higher Special Attack than Mew, Venusaur and Starmie, and Blissey wasn't there to outclass it), BL in GSC and BL in Advance. And many other communities still have Chansey in BL (although their UUs are filled with Pokemon like Meganium, so I guess that's understandable).
Chansey definately is not on the "sucky side" of UU. Chansey is the best Wish Passer and Special Wall in the tier, because of its one weakness to Fighting. The Lack of Aura Sphere in this tier makes Chansey nearly impossible to get passed with Brute Special Attacks.Overall, I feel Chansey is on the sucky side. It's too vulnerable to Taunt, which renders most of its options useless (Save Seismic Toss), so basically, it becomes set-up bait for any Ghosts with Taunt (aka Spiritomb and Mismagius)
Even otherwise, any decent physical sweeper can set up on it after a Taunt, as well as Substituters, who don't need Taunt to function. Personally, I find Ground-types like Torterra and Steelix laugh in it's face, as it does not carry anything to hit them, in fear of losing other valuable moves.
Edit: It is kind of funny that Pokémon like Chansey are in UU now. You could make the same statement about Claydol, who was UU(im assuming you mean OU) in Advance, and has been UU for a long time now. Also, Arcanine was UU in RBY, and I think it was in GSC. But they fit in pretty well, so I'm pretty sure they're here to stay for now, save Raikou, who is on the verge of being deported from UU.
I understand it's probably the #1 wall specially, but physically, it can't do much, and many STAB physical attacks will rip right through it. Other special walls can do much better than Chansey on the physical side, whereas Chansey can only Wish+Protect Stall, use Thunder Wave or Softboiled, or switch out, and it can't even do that safely. Like Blissey sometimes, it becomes set-up bait too easily, especially for more offensive people like me.I don't see how Chansey can at all be on the "sucky side". It singlehandedly counters all the Special Attackers in UU (barring Mismagius and possibly Spiritomb) plus has access to Wish to support the team.
I understand Chansey can take quite a few hits on the physical side if need be, but it is outclassed by other special walls in that department. If you can bring in something like Staraptor or Gallade; heck, even stuff like Hariyama, Hitmonlee, and Primeape will tear it up. I'm not saying it's bad. It's very good at doing its job, but if it ever gets tossed into a situation where it has to function differently, it can't do it.Thanks for the input. Though, I feel that some people haven't really used Chansey based on what they've posted. First off, Chansey can take a physical hit rather well and people underestimate her massive amount life to compensate for that horrific base stat defense.