Having seen this game being available on a lot of multicartridges, and so far, I have seen no difference in the gameplay. Is it allowed? Also, is the hack "Coin Tetris" allowed as well? Or does it have to be just the game rom by itself?

If the game is no different from the original, I think you can use it. But original rom is preferable, ofc

Thank you for the response.

Did u guys know about the baby faces versions of the game? I've been searching for it for DECADES!, these version shows baby faces shaped blocks in the advanced levels, and make a silly noise when you align them.