Shiver

• Invite amiibo-exclusive villager Cece / Unlock Splatoon-themed items in shopping catalog

Community-reported

• Unlock Splatoon-themed catalogue items and invite a special crossover visitor; the visitor depends on the amiibo.

From NintendoSource

• Unlock a special costume

Community-reported

• Unlock a Splatoon-themed racing suit

Community-reported

• Receive a random title or avatar item, up to five times a day. Each amiibo can be used once a day.

From NintendoSource

• Revisit the Grand Festival Grounds to see past Splatfest performances
• Unlock exclusive gear / Save favorite weapons, gear, and control settings / Take photos with the character or saved gear

Community-reported

• Receive special clothing

Community-reported

• Unlock a Splatoon pattern

Community-reported

• Unlock randomly assigned three-minute NES or SNES game scenes. Subsequent scans change the scene.

From NintendoSource