first, have the ghost of a friend who is lvl100, then get a lvl_ character and spam an attack. With my lvl 1 Zidane constantly using tidal flame on ground while vsing my ghost (im playin for my bro) which was a lvl100 Tidus, i lvled up 20~30 times. the more hits u land, the more exp :D and at lvl 1 i got an average exp for each character of about 4000exp per hit. Hope it helps.