When you have to select the order of the characters, first hold START and a face will appear on each character. The colour of the face shows whether the pwoer stocks will be conserved or whether you'll lsoe all of them when you control the next character.

White normal face: the power stocks will get passed on
Yellow smiling face: the power stocks will get passed on and you'll get one more too
Red angry face: you'll lose all the power stocks