amiibo are a series of "toys to life" based on characters from Nintendo franchises. Using an amiibo can wield various results such as bringing a certain character into your game and awarding certain bonuses.
The first (and currently only) Xenoblade Chronicles-related amiibo to be released is the Shulk amiibo, released as a part of Wave 4 of the Super Smash Bros. series of amiibo on February 1, 2015 (as a GameStop/EB Games exclusive to begin with in North America). However, Super Smash Bros. series amiibo for Pyra and Mythra from Xenoblade Chronicles 2 to are slated to be released in Spring 2022.
The following is a list of games that are compatible with amiibo and feature specific functionality for those of the Xeno series. Games that treat such amiibo as "other" are not listed.
Chibi-Robo!: Zip Lash
Using a Shulk amiibo in Chibi-Robo!: Zip Lash unlocks a statue of Chibi Robo mimicking Shulk's pose.
Kirby: Planet Robobot
Super Mario Maker
Super Smash Bros. 4 and Super Smash Bros. Ultimate
Using a Shulk amiibo in Super Smash Bros. for Nintendo 3DS, for Wii U, or Ultimate brings a Shulk FP (figure player) into the game, which can fight alongside or against the player to have it learn techniques, gain experience, and be customized.
Using the Shulk amiibo in the 3DS port of Xenoblade Chronicles once per day in Collection Mode gives the player three tokens, which can be used to unlock character model viewers and music to listen to in the main menu.
(Poochy &) Yoshi's Woolly World
An amiibo can be scanned three times a day to receive bonuses, mainly EXP or collectibles that spawn after closing the menu. Using the Shulk amiibo for the first time unlocks a Monado skin for Noah's Swordfighter class. It can also be unlocked by clearing the game, even without the amiibo.