I did this list at the suggestion of another group member on "Padded Ponies and Adult Foals" almost five years ago. Back then I restricted myself to just the three alicorn princesses (Flurry Heart and Twilight were excluded). Since then there's been at least more one princess character to consider, as well as one that technically counts as a princess even if it's unclear if she still has that title. I'll still be excluding Twilight since everything I could say about her I already said in my second version of my mane eight ranking, but all the other princesses are fair game. Of course, this is just my personal opinion like it is with all the other lists. So feel free to let me know what you think. And here's the original if you're interested.

6. Princess Flurry Heart: We only saw her as a baby, back when she needed diapers. And unlike the Cake Twins she never got out of them on-screen (the only indication that the twins were in fact getting older). Of course, that does mean she's a blank canvass for when she gets older. But I have a feeling that at least in the short term she did have to eventually give up diapers and learn how to use the potty like other foals. It's anyone's guess how well that worked out or whether that played any role in how she came to view her time in diapers. There have been a few fics exploring this possibility, but not a lot.

5. Princess Cadence: Of all the "grown-up" princesses, or at least among all the alicorn princesses to be grown-up more or less, I really don't see much that would compel Cadence to enter into the world of AB/DL. That may explain where there's so few fics where she's the baby, more often than not she's the caretaker. Now, if we take some expanded media into account, particularly the chapter book that more or less gave us her backstory, it's possible that she may have to had grow up sooner than she would've liked. But she was already past the toddler stage by that point, so I don't know if that would be a motivator in her wanting to be that young again. At least she has something compared to Flurry Heart.

4. Princess Ember: She doesn't have a love of cute, silly stuff like Smolder did. But from what we can piece together I don't think dragons diaper their young (probably because the usual material wouldn't survive all the lava, smoke and flames, not to mention claws. And any material that could be used as a substitute wouldn't be very comfortable or absorbent). That could be one avenue to look into if Ember ever were to be curious, maybe even secretly jealous because Spike got to experience stuff that she didn't. There is also her lack of understanding about pony customs, which could also be what lead to her padding up initially. Maybe she'd stick with it or maybe she wouldn't, it's hard to say.

3. Princess Celestia: Even taking into account her canonical retirement and the free time it would give her, Celestia still seems like the motherly type better suited to being a caretaker. But I imagine she might take an interest in diapers just to see what it's like, or just to have a break from always being the one everyone looks up or turns to in a time of need. That does fit in with what "A Royal Problem" established about her frustrations with her daily routine, but she would likely indulge in secret and only on the side.

2. Princess Luna: We don't know how exactly the dream realm/world works, so maybe Luna already wears diapers as a possible form of protection while patrolling other ponies' dreams. She never seemed to be particularly annoyed or bothered by her little sister status, and we don't know how long it took her to get back to what was more or less her "full power" design from Season 2 onwards. Who's to say she wasn't at least somewhat in diapers during all that off-screen time while she re-learned things, including how toileting customs almost certainly changed during her thousand years of absence? Heck, she could turn to it as a coping mechanism that she takes up in secret, not that I think Celestia would do much other than maybe tease her a little at first. And yes, there's the whole "Gamer Luna" thing that the fandom still goes nuts for.

1. Princess Skystar: Like Pinkie Pie, Sweetie Belle and Izzy Moonbow, Skystar has the whole "Child at heart" mentality that Silverstream also had. She doesn't have quite the same level of it as Silverstream, particularly noted by the fact that she doesn't fear the Storm King like Silverstream did. And it's not clear what happened to Skystar's father/Novo's husband, or how old Skystar was when the hippogriffs fled to Seaquestria. So there's already a lot working for her to become an AB/DL, though strangely enough despite a little bit of padded artwork about her there have yet to be any stories featuring her. Maybe that's because of one thing that could be confusing to think about: Underwater diapers. Yeah yeah, I know I'm probably thinking way too much about it, but how would they work exactly? Would they be ordinary diapers modified for underwater use so they wouldn't immediately fill up with sea water? Or would they be custom made with underwater materials? If we were just talking about Skystar as a hippogriff, that wouldn't be a problem since any kind of diapers would work well. I mean, she had to have been a baby at some point, right? With all that's expected of her as heir to the throne, what's to stop her from wanting to return to a more carefree time in her life?

And there you have it.