You'll meet certain characters throughout the game who will ask for passwords. By telling them these passwords you may battle them in which they become available for recruitment via capsule machine, or if it's not a team password, they outright join you.

Effect	Password
Andy (linked to Aurelia)	Letsplay
Aurelia (linked to Andy)	Football
Bernie (element team)	Elements
Deck (The Card team part 1)	Buildadeck
Gouger (Halloween team)	Pumpkin
Howler (Halloween team)	Fullmoon
Isaac	William
Jordan	Word, ends well, believing, merrier
Pogue (The Card team part 2)	Fullhouse
Quagmire	Gungnir, epsilon, Kyoto, Gaia
Stickler (team)	Followrules
Vicked (Halloween team)	Broomstick
Wraps (Halloween team)	Wrappedup
Zolletta	Cappuccino