In Paper Mario: The Thousand-Year Door, Goombella attends a university called U Goom. While this is not a pun on any specific university in English, other languages make it a Goomba version of various real-life universities.

She graduated all these top universities in at least 7 different languages? No wonder she was allowed to cameo in Sticker Star!

i thought old paper mario stuff was Verboten since sticker star, very interesting

Yeah, that's definitely not the case.

Appearing in game is at least (outside of Smash trophies/spirits and stuff)