Are you talking about the Schematic Cards? If so, from the Rulebook posted online:
Schematic Cards are powerful Yordle-specific abilities that require Team Gears to activate. At the start of each Mission, each player chooses up to two Schematics to bring to the Mission. The player can choose any Schematic unlocked so far, but only Schematics associated with the Yordle they are playing as.
thank you, yes this is what I was talking about!