Character: mad mew mew
Mad Mew Mew is a character exclusive to the Nintendo Switch and Xbox One versions of Undertale. She is the same character as the Mad Dummy, albeit inhabiting a Mew Mew doll that once belonged to Alphys.
In the Switch version, she can be fought as a bonus boss hidden inside of the Dog Shrine after defeating Mettaton EX. She believes that fighting the protagonist will help her integrate with the doll body, but is eventually convinced to stand down, at which point the player can choose to SPARE or ATTACK her.
In the Xbox One version, again after defeating Mettaton EX she takes Sans's place at the Dog Shrine, which has been converted into a casino. She has her own set of commentary for the various items the player can obtain in the casino.
