From the Super Mario Wiki

  • image – an image. Must use {{!}} for a | break symbol in image syntax.
  • title – default pagename, just in case can be changed
  • first_appearance – the game this form debuted in
  • latest_appearance – the latest game this form appeared in
  • item – what item gives Mario this form
  • powers – the powers Mario gets in this form
  • character – which character uses this form

All of these can be left blank and will not show, but fill in as many of the details as possible, of course.