I feel like, in this AU, Twilight being a pony would be common knowledge, and her usage of terms like "everypony" and "sweet Celestia" would be an inside joke inside their friend-group. Maybe when she first joined, she and Finn could bond over how awkward it is for them to use certain phrases in whichever world this takes place in.
Sure♥️ 1.Adventure Time 🧁⚔️ 2.Star vs forces of evil🌟👸 3.My little pony friendship is magic🦄🌘 4.Steven Universe 🌺💎 5. Over the garden wall (a Halloween TV show, there are only 10-12 episodes)🍂🕷️ 6. Gravity falls 🌠📕
It's Fin from Adventure Time Star of Star vs the Forces of Evil Twilight from My Little Pony: Friendship is Magic Steven from Steven Universe Wirth from Over the garden wall Dipper from Gravity Falls