Hello mods! A little question for you: how much headcanon is accepted for items? Are implied things ok?

If you need the full story: Bianca explicitly uses Fly in game (hell, she even gives the HM both times) but none of her canon team members can learn it. So I usually headcanon she has a Flying-type she uses to explore - he isn't strong or anything, can hardly battle, he's just a support mon. Would it be acceptable to ask for him?