If you're playing Picross 2 with the Super Gameboy, you can change the color of the border if you hold a button or the control pad in a specific direction before pushing Start. Hold Left and press Start to get a Green Border, Hold Right and press Start to get a Red Border, Hold Up and press Start to get a Black Border, Hold Down and press Start to get a Yellow Border, Hold B and press Start to get a Grey Border, Hold Select and press Start to get a White Border.