Interesting, after testing it out it seems like Ditto's analysis has some misleading info on it. It has some descriptions of using certain IVs to get certain Hidden Power types, but if this isn't needed then it's suboptimal. Idk why I just assumed that because it was on an analysis it was true, should have learned that from the old gliscor analyses lol. I'll edit it soon
edit: I’ve been told there’s a teambuilder glitch regarding Ditto hidden power; I’ll hold off on this for now
I'm retired from playing and only happened to come across this while randomly lurking, so everything I say very well could be off, and if that's the case, I preemptively apologize.
I thought that in gen 7, a mon's initial IVs did determine its Hidden Power type but that you could use Bottle Caps to max the IVs anyway. So, if I'm correct about that, how it would work on cart is that a mon still needs to have whatever specific IVs correspond to the desired Hidden Power and then you can make them 31 or whatever you want afterwards; I don't know how that works with getting 0 IVs in Attack and/or Speed and still getting the Hidden Power you want but I assume that there is some combination of IVs that could work for every type while having those stats with 0 IVs.
I remember from back when I used to play that the builder is glitched/weird when it comes to Hidden Power types. I definitely remember that even though you can pick the Hidden Power type from a separate drop down and then set the IVs, every time I first loaded Showdown I would have to reset some of the IVs to 31 on my Lando and AV Mag because they would get set to whatever the optimal IV spreads would have been prior to being raised through Bottle Caps - if what I'm talking about is confusing,
I found my post in the RoA Simple Questions thread from years ago that may explain it better. I'm not sure if this ever got fixed but it at least used to be a minor inconvenience.
So, to tie it all together, I don't think that
the analysis on Ditto is necessarily incorrect, but it's weird due to how the builder handles IVs and HP types. The analysis says that 0 Speed IVs and 31 IVs in every other stat corresponds to HP Ice, and since that is the recommended Ditto spread, I actually imagine that the vast majority of the time, Ditto will use HP Ice. I think that the other user (
YubelVT) was confused because they thought that Ditto copied their mon's HP type but the reality is probably that they both had the IVs for HP Ice; if their mon had HP Flying or something, the opposing Ditto would still have had HP Ice.
The weird part is just that the builder has an option to set the HP type, since there isn't really a better way to emulate the on cart mechanic of a mon having its original IVs and then increasing them through Bottle Caps, but on cart you never have an option to set your HP type. It works for the most part on Showdown (except for the glitch that I mentioned where the builder resets the IVs from 31 to what would have been the ideal IV spread for whichever HP type, although that may have been fixed at some point), but Ditto is unique in that it can't learn Hidden Power on its own, although it can copy it. You can still use whatever IV spread you want on Ditto and choose the HP type you want in the builder, and the Ditto will use the HP type you chose after copying an opposing mon -
I tested it in this battle and even though I used 0 Speed IVs and 31 in everything else for Ditto, since I set its HP type to Ground, it knew HP Ground after transforming into the Thundurus-Therian that had HP Ice. That isn't a mistake with the builder and should be replicable on cart, since the Ditto would have just needed to originally have IVs that lined up with HP Ground and then have used Bottle Caps to max everything except for Speed.
I think that the only place where the analysis for Ditto may be off is when it says, "30 Special Attack, 30 Special Defense, and 1 Speed IV can be used for Hidden Power Ground, which allows Ditto to countertrap Magnezone." That isn't technically incorrect, but I think that you could still use 0 Speed IVs and whatever other IVs to get HP Ground and then increase everything else except for Speed with Bottle Caps, or at least the builder lets you achieve this with setting Ditto's HP type to Ground and then making its IVs the optimal spread (0 Speed, 31 of everything else, although I guess Special Attack and Special Defense wouldn't matter).
Sorry for writing so much - I hope this made sense and like I said in the beginning, I sincerely apologize if I'm wrong about anything. I also never planned on posting on Smogon again but I saw this very niche and specific topic that I may have some insight on and couldn't resist lol.