StreetPass is a feature on the Nintendo 3DS that allows players to exchange data with others' 3DS consoles. It works when wireless communication is on, the 3DS is in sleep mode, and is not near a Wi-Fi network (that would instead activate SpotPass).
Use in the Kirby series
Kirby: Triple Deluxe
Kirby Fighters Deluxe
In Kirby Fighters Deluxe, while not used in the game itself, if StreetPass data is detected for Kirby: Triple Deluxe, the player can use Bell and Beetle in the game, and can also play on the Waddle Dee Train Tracks stage.
Dedede's Drum Dash Deluxe
Similarly to Kirby Fighters Deluxe, Dedede's Drum Dash Deluxe does not use StreetPass itself, but if Kirby: Triple Deluxe StreetPass data is detected, the player will unlock masks based on Kirby, Meta Knight, and Waddle Dee.
Kirby: Planet Robobot
The use of StreetPass in Kirby: Planet Robobot is the same as in Triple Deluxe, but allowing the exchange of stickers instead of keychains and Meta Knightmare Returns records instead of Dededetour! records.
Team Kirby Clash Deluxe
In Team Kirby Clash Deluxe, while not used in the game itself, if StreetPass data is detected for Kirby: Planet Robobot, the player will unlock the Susian Bolt Blade and Haltonium Helm to buy in Magolor's Shoppe.
Kirby's Blowout Blast
Similarly to Team Kirby Clash Deluxe, Kirby's Blowout Blast does not use StreetPass itself, but if the 3DS has StreetPass data for Kirby: Planet Robobot, then after the first stage, special statues of both Kirby in his Robobot Armor and Susie in her Business Suit are added to the Plaza and change the background music to "Flight of Azure" from the same game.