This game is also available on GBA.
BLACK, DOWN, R, L, DOWN, Y. you should here a voice say " ooh "
then quickly press l,black,right,x,left and then r,left,b,down,white, then click on the gnome which will appear in the front garden
L, BLACK, RIGHT, X, LEFT. A Gnome will appear near the post box.
L, R, A, DOWN, BLACK