>>37112156IVs are usually called "potential" or something, but I think whatever Hyper Training calls them is probably best because it's likely the most specific and explicit term. Base stats are for EVs, not IVs.
In any case, that one's easy to justify getting wrong: we already call something else "base stats" and it would be a needlessly confusing change to make on the whole (not to mention that you'd almost inevitably end up with some people using base stats for their current use, which doesn't seem to have any consistent official name, and some people using them for EVs - it's just not worth being so pedantic about official terminology that you obscure the actual meaning of the term and actively make it more ambiguous what you're talking about).
Meanwhile, friendship vs happiness is a fairly easy change, but it's also not at all an important one. What difference does it actually make?
(And implying that Serebii correcting himself is going to change anything is pointlessly naive. People have refused to get Legendary vs Mythical right for years even after Bulbapedia finally corrected itself, and even when people do use Mythical right, they still often seem to think it's a subset even though it's officially not. The reason for this is simple: literally no one cares. And what reason is there to care??)
Anyway, I use friendship correctly and distinguish Legendary and Mythical and am familiar with most of the other official terminology, but that doesn't mean I see a need to correct anyone when they get it wrong. It's just... not as big a deal as OP seems to think. It's one thing if someone literally asks the difference and you tell them, or someone wrongly answers "Mythical is a subset of Legendary" or "the official term is happiness, not friendship," in which case it's worth correcting them because that's the whole substance of their message - but if it's just someone casually calling Victini "Legendary" or friendship "happiness," what's the point in correcting them?
