Button Function
A ROM menu
B VMU menu
Y Credit
START + Y + L + R Reset

ROM Menu

Button Function
A Move to the directory
Y Move to the parent directory
X + D-pad Accelerate cursor
Analog stick Adjust cursor wait

In game

Button Function
X Gameboy B button
A Gameboy A button
Y Gameboy Select button
START Gameboy Start button
D-pad Gameboy D-pad
L + R + START Exit game
R + B Quick state save menu
R + Y VMU state save menu