PSP characters

Ok, I don't know how to unlock Luigi & Sarge (not even sure is Lizzie & Fillmore can be unlocked to ), done the Story Mode (unlocked DJ, Snot Rod, Wingo, Boost & Chick) done the Grand Prix (unlocked Doc Hudson, Sheriff, Flo & Ramone) All I'm left is these 2(+?) characters, do I have to beat the time trial or something?

How long...can any man fight the darkness...before he finds it in himself
Next summer...the greatest battle…lies…within…3…May 4th
281 Days - Spider-Man 3