L-Shoots the current element ghost you've capured (fire, water, ice).
R-Use your vacuum.
Z-opens up the items / ghosts list.
Control Stick-the harder you hold it, the faster Luigi moves. (standard) Moves either forward, backward, left or right.
Start-Pause the game.
Y-shows floor map. Use control stick to change floors.
X-Shows from Luigi's point of view.
A-The basic button. Examine objects, open doors, display next message if talking and choose an option.
B-Turn flashlight off in dark room.
C-Stick-Change direction of flashlight or vacuum. (standard) turns Luigi.