Watching a video about the toddler stage life, I discovered that the toddler formal wear is apparently bugged? I got no further explination on why/how it's bugged. I googled it, as I should, and I only got info about Sims 4, and other bugged clothes that wasn't specific enough.

Is this... news to anyone? It's news to me. I've never heard of this. You'd think with all the expantion packs EA/Maxis came out with, they'd do something about that. Maybe they didn't know?

It's not bugged. It's just not accessible in early EPs, because it wasn't added in a category until later. Bodyshop still doesn't show formal, athletic or swimwear for toddlers, or show child athletic clothing.

Well if bodyshop doesn't show formal wear for toddlers and athletic wear for kids (swimwear and athletic wear for toddlers was never officially introduced, so it's completely irrelevant) then that sounds either bugged or a ridiculous oversight on the hands of the developers, after all, the Bodyshop does show outer wear, which was also introduced in an EP, so why not those two EP-additions?
What I'm saying is that athletic wear for children and formal wear for toddlers were officially implemented in EPs, there was a new version of Body SHop with each EP, so they shouldbe accessible in Bodyshop.

Weirdly enough there's an "Underwear" category for Toddlers in Bodyshop with only a single pair of diapers....when do Toddlers ever wear Underwear?

Some custom splash pools change them into underwear. Not that it explains why Maxis would give them some. But as you mentioned before, Maxis makes no sense.

Precocious potty-trainers? As a mother of two children born in the 90s, and talking to other mothers back then, potty-training often started around two years of age, and I recall some mothers starting earlier to try to get their kids into certain childcare facilities. Believe me, if a toddler turned out to be a potty-training prodigy, we heard about it!

Also, even in the 90s, we had pull-up training pants. Those kind of look like undies, if you squint. So maybe Maxis was thinking about those?

Or not. And I think I might be derailing the topic, soooo ....

I would go along with this. As soon as a toddler would be potty-trained, he would not need/wear diapers anymore, he would start wearing Undies. It would make sense to create a Undies category for them, but then...all the toddler clothes Maxis have made all look like they are wearing a diaper underneath. Good intentions, bad thinking?

To explain; I didn't mean when actual toddlers around the real world might wear underwear, I have nephews . I meant that, to my knowledge toddlers never change into underwear during a vanilla game (only in some CC, apparently, as Charity helpfully pointed out) so it's weird that there's a Bodyshop category for Toddler undies (which constitutes solely of a pair of diapers) but no Bodyshop categories for Child Athletic Wear or Toddler Formal Wear (here I can at least guess that quite a few players take the time to dress up their toddlers for weddings)

Orphalesion, now that you mention it, I have never seen my toddler sims in their underwear. Not the concept of underwear, but the actual outfit. Maxis has you pick from that one outfit in CAS, but what's the point? I never, ever see the outfit...

Yeah, I was also talking about Sims 2 toddlers.