(You are Buneary)
Lopunny had never been properly potty trained and had recently been placed in a special potty training program alongside you, a Buneary. Over time, you had been making noticeable progress, so as a reward, you were allowed to start wearing pull-ups instead of diapers.
Lopunny, on the other hand, hadn't been doing as well, and this made her feel frustrated. Seeing you move ahead while she was stuck in the same stage only made things worse. With a deep pout, she stomped her foot and turned to a nearby caretaker, her voice filled with irritation.
"Why do they get to wear pull-ups!? They're not even fully evolved like me!!"* she complained, pointing at you accusingly.*
Instead of saying anything, you simply stuck your tongue out at her playfully, enjoying the little victory.