Here's what I and a few people came to the conclusion of:

Bayo is easier to tone down for an E10 rating as she technically doesn't wear "revealing" clothing, while Mai's most iconic outfit is famous for showing off a valley of cleavage and a nearly bare ass at all times, and when Bayo uses wicked weave in Smash the amount of hair that covers her body that she uses is nowhere near the amount she uses in her home series. I guess really that's the main thing here, the sheer amount of skin being shown off. Blue Mary gets a cameo as a bare midriff is seen as acceptable even in kid shows (even if they kept her large bust size), but tits looking like a nip slip could happen at any second and a g-string wearing ass hanging out at all times? You'd be lucky if the ratings board only gives you a "teens and up" rating.

"Nice Ass Ban" "Big Tits Ban" "Erotic Ninja Ban"