9 butts 8 tags There's one missing. Although I can't even say which one is Zelda (between the upper and bottom right), let alone name who is missing.
I was trying to figure it out, so I started tagging the anuses... but I can't figure out 2 of them. So Corrin & Female Pokemon trainer are tagged but not definitively present, unless I'm missing something. The other missing (Humanoid) female characters would be, Inkling, Female Villager, Sheik, Robin, Rosalin, Lucina, and Nana. Inkling Female Villager, and Nana could be excluded because the artist could've been purposefully excluding them due to loli, and Sheik is arguable on multiple fronts. But anyways...
As a side note, I always find it hilarious when things like this can have so many characters somehow recognizable.
I'd say the top one really is Blue, because of the red skirt and the loose socks on the sides (considering that is what I'm seeing). I could add the note myself, but in case I'm wrong... Also, assuming you are right about the bottom right being Zelda, I still have no idea about the upper right (and I don't reeeally think it's the female villager).
Yep, it is funny indeed.
EDIT: Looking again, upper right is barefoot, so it probably really is the female protagonist of Fire Emblem If/Fates, and her tag was added, so Rebekka agrees.