From Nookipedia, the Animal Crossing wiki
Katie (まいごちゃん, Maigo-chan, Lost Child) is a yellow kitten with brown hair who will randomly appear in town one day, once the player's gate has been opened and a visitor from another town has been accepted. She will cry and tell the player that she has been separated from her mother, Kaitlin, and that she believes her mom is in the aforementioned visitor's town. Once the other town has its gates open, the player may request to visit that town. The day following her reunion with her mother, the player will receive a present in the mail; the player who had Kaitlin in their town will get nothing.
Katie walks slower than the player and may get left behind or fall and cry.
In Animal Crossing: New Leaf, Katie once again appears randomly in the player's town one day, once the player has interacted with someone from another town. This time, Katie is now by herself and wishes to see the multiple towns of the world, telling the player that she wants him or her to take her to the player's friend's town. She will also say which towns she has previously visited. After exiting the train, Katie will mention that the main reason she decided to follow the player to the other town is that she is uncomfortable traveling alone. A day later, she will give the player a thank-you present.
Animal Crossing series amiibo Card
Katie, along with Kaitlin, appears as a spectator in the Smashville stage, and as a trophy.
Katie appears with Kaitlin once again in the Smashville and Town and City stages, however, Katie has a standalone trophy, unlike Brawl.
The following furniture items are available as rewards only through this method.
Names in other languages