This is a bit confusing. You make blatant references to the bulky attacker set, but there's no mention of it at all in the analysis. Only a little rewording is necessary, but perhaps you could mention it in OO, or even in Set Details of the first set? Oh and as far as "type counters" go, don't you think that it looks a lot easier (and cleaner) to simply group them all together as "Special Walls" and "Ground-types"? Doryuuzu and Hippowdon do pretty much the same thing as far as checking Mega Amph is concerned (switching in, not minding either of its STAB, and threatening with a STAB Earthquake); in a similar vein, TTar, Nattorei, Chansey, etc are all fantastic Volt Switch sponges that are also capable of beating SDef Amph (or, at the very least, are capable of shortening its lifespan significantly).
Oh, and, OO can be expanded a bit, with one of the most notable options being Discharge. I'm a bit taken aback that everyone is so adamant on Volt Switch always being the superior option to use ("becuz momentum"). Spreading paralysis not only helps Ampharos in the long run (really helps with TauntTran, super ballsy Mega Mawile, Mega Gardevoir, Mega DDTTar, Mega Venu, and can be used for hax in general), but it can be also be used for solid team support if Ampharos is to be used on something more... defensive. Lastly, in the previous thread, someone made a mention of a fully specially defensive set. The calcs they'd provided showed a very large difference in defensive capability (doing things like taking LO Lando's EPand OHKOing back with HP Ice), and for that reason, I think that it deserves a fairly modest mention in OO with the label "Sacrifices a lot of power, but tanks 'X', 'Y', 'Z', etc much better", or something along those lines.
I'm not QC, but I've used this thing more than enough for my word to be valid (also, those who I practice with can attest to the effectiveness and downsides of Discharge and Volt Switch, respectively).