The A button can be used to skip the happy cutscene when a Mii is fed their favorite food.
Tomodachi Life Controls
Pressing A or down on the directional pad can skip texts and certain cutscenes.
Pressing X takes a screen shot of the top screen of the 3DS. Pressing Y takes a picture of the touch screen.
Pressing L or R when inside of a Mii's apartment changes the top screen from the [Mii's] information to [Mii's] list of friends.
Using the circle pad before going into a Mii's apartment will turn the camera angle around the room, allowing the player to see more of the room.
Pressing down on the directional pad or the B button while a cutscene is showing or when a Mii is talking will skip the speech or the cutscene.
When pressing down or up on the directional pad while the touch screen shows a list of (food, clothes etc.) the orange rectangle will change the position.
When a Mii is sleeping in a bed in their apartment and their head is touched, a drawing mini-game shows up.
When touching a bubble over a Mii's head they will say something or they will show their problem.
During a Photo Studio, a holiday, or when using an AR camera, when the camera's button is touched it takes a picture.
When a Mii is going to propose, the mini-game has a heart on the bottom screen saying "NOW!" The player has to touch it to signal the Mii that their sweetheart is thinking of them, as shown by their face appearing in the sweetheart's thought bubble.
When in the Mii Apartments, tapping a window will show apartment of the touched window.
When in mini-games, everything is done with the touch screen.
When in a Mii's dream, if the player has to do something it's usually done with touch screen.
When selecting something from a list, the touch screen can be used to search from the list.
The touch screen is used to write sentences like in Quirky Questions and songs.
During the Flying Disc event, the player must fling their stylus on the touch screen to throw the frisbee.
The touch screen is used to edit Miis in Mii Maker.
When a Mii successfully proposes to its sweetheart, the touch screen can be repeatedly tapped to applaud for the couple.
When touching the thought bubble above a sleeping Mii, the player can see into its dream.
When at Mii apartments, you can use the stylus to interact with the Mii. You can pat its head, spin it around, view their face/belly/back in close-up, make them sit down/lie down/roll over/jump, make them blush, have them "work on their funny faces", X-ray their head or belly, or pluck things off them.
The gyro sensor is used to show the player's face to scare the Mii in the Giant dream.
The gyro sensor is used to take photos of the player in the park.
During the news that a Mii has its birthday you can blow off the fire from the candles during a scene.
When the mobile is used it moves if the player blows to the microphone.