In Undertale Shimeji - Sans, Frisk & Asriel, you can find lots of character stickers from characters from the Undertale game, as well as other characters from other games. You can choose a character from the list on the side menu, and you can use it to make your animated sticker.

It supports Sans, Frisk, Ariel, Flowey, Papyrus, Chara, Undyne, Napstablook, Grillby, and many other characters. You can add more than one sticker at the same time. You can set many of them to be on your screen at the same time, and each character has its unique animation.