From Nookipedia, the Animal Crossing wiki
Isabelle (しずえ, Shizue) is a dog that first appeared in Animal Crossing: New Leaf, where she helps the player with their duties as mayor. Her name was first revealed as Hisho during the New Leaf developer commentary, then changed in the June 2012 Nintendo Direct to Shizue. When localized to English, her name became Isabelle. It may be based on the fact that the top of her head resembles a Bell sack. Her Japanese name comes from shih tzu, the breed of dog she is based on.
Because she was the first new character to be revealed to players, many people speculated that she is the 'eager secretary' that will assist the player in his/her new role as the town mayor. This was later confirmed when she was shown talking to the player, with the name Hisho (ひしょ), which is Japanese for secretary, during Tokyo Game Show 2011. She is said to be very clumsy and very absent-minded. She has a twin brother named Digby who runs the Happy Home Showcase.
Isabelle makes a cameo appearance in the first E3 trailer of Super Smash Bros. for Nintendo 3DS and Wii U. She appears in the game as an Assist Trophy.
Isabelle, along with the villager, appears as a playable racer in the second Mario Kart 8 DLC Pack, which was released in April 2015.
Isabelle's main role in Animal Crossing: New Leaf is to act as the player's secretary and to help them with their mayoral duties. At the start of the game, she helps the player settle in by offering them advice, as well as providing them with optional tasks akin to those given by Tom Nook in previous games. In addition, she also helps the player earn their development permit, which allows for the enactment of ordinances and the construction of public works projects, by helping them attain a 100% approval rating and, when the player's house is built, making them a resident of the town. When the player gains the abilities to build public works projects and enact ordinances, she assists the human character with those as well, including the ceremonies when projects are complete.
She spends most of the time in the town hall, but is also the main character to stand in the plaza during events. During such events, the town hall is closed, preventing the player from performing their mayoral duties.
Isabelle takes over Mr. Resetti's role of reminding the player about saving until the Reset Center is built. She may be caught sleeping in the town hall a week after the first public works project is built, and this will allow the Dream Suite to be built on Main Street.
Isabelle is now an employee at the Town Hall and gives the player Public Facillity projects, because she has heard of the player's renowned house-building skills. She can also have a home built for her by scanning her amiibo card via the amiibo phone located in Nook's Homes.
In Super Smash Bros. for Nintendo 3DS and Wii U, Isabelle has a plethora of roles, each of varying degrees of importance. The secretary makes an appearance as an Assist Trophy, replacing Mr. Resetti as the sole Animal Crossing series Assist Trophy. Once summoned, she tosses fruit at the player who summoned her, which heal them upon contact. However, only the summoner has the advantage of being able to recover by simply touching the fruit; the other players can heal via the fruits, but they first must pick them up and use them as if they were an item.
In addition, Isabelle is a Smash Tour item that, when used, causes all the nearby stat boost items to grow to their maximum size.
A Mii Fighter costume based on Isabelle - consisting of a hat and an outfit - was released as downloadable content on June 14th, 2015. The headgear can be adorned by all three varients of Mii Fighter, while the outfit is only available for the Mii Gunner (with the standard gun being replaced with a party popper).
Isabelle is a playable character who - alongside the Villager - is part of the downloadable content pack Animal Crossing x Mario Kart 8, which was released on April 23, 2015. Her signature vehicle is the City Tripper, and she is a lightweight racer.
Name in Italics denote PAL Name.
"Isabelle is here to support whichever fighter summoned her into the battle. She'll throw healing fruit that's used just by touching it."
"Isabelle will do her best to throw the fruit she brought to the fighter who summoned her. This doesn't mean other fighters can't steal it."
"Isabelle cares how the fight is going! If the fighter who summoned her gets a KO, she'll be happy! She'll flinch if the fighters get close."
In Happy Home Designer
Names in other languages