In SMB Episode 23 Link comes back to warn Mario and Luigi about the Darkness.
Mario,luigi and link talk


Link calls Mario and Luigi's names and Luigi asks How Link got here because all the pipes are broken but Mario points out Ash and Brock's works.But Link says he has something important to tells them and Luigi asks if it's about the Darkness Link says it is.Link says The Darkness is a real person and that it can Copy who ever it comes in contact with.Mario says if it was him and if he Touch Luigi (Which he does and Luigi turns into a Mario clone)He would turn into a clone and Link says yeah."Luigi"Asks what they should do and Link resonds "Wait." and Mario asks if he means wait as in wait here and do nothing wait but Link say wait as sit here and wait for something to happen wait."Luigi"says nothiny will happen if they just wait.Link then says "Okay.YOU MUST DIE!"