Here are a few of my thoughts in response to some recent nominations;
- Blissey/Chansey- While Chansey has much better bulk on both sides, she's not really much better as a special wall than Blissey if at all. The difference in how they take special attacks is miniscule in most situations, so they both perform that job admirably. Chansey can take physical attacks here and there, but lots of physical Pokemon beat her anyway (particularly Fighting-types.) Chansey definitely outperforms Blissey nine out of ten times, but Blissey isn't heavily outperformed so often. She has benefits in passive recovery and usable SpA (frying Ferrothorn with Flamethrower on the switch is always nice,) which give perfectly valid reasons to use Blissey. Meanwhile, the weaknesses they share are basically the same. Both struggle with strong physical moves and are generally set-up fodder. Neither wants to take a Knock Off, nor do they fare well against common users of the move, so that's a moot point. Special Walls are still a great asset for slower, stallier teams, and this is basically as good as you can get. Both of these mons are fine as they are ranked.
- Hippowdon- I can certainly see this guy going up to A-. As a physical wall, Hippowdon excels. He's certainly let down by sub-par special bulk and average/poor defensive typing, but the ability to shut down physical attackers so well is incredible.