Weakest:

Aeris (FFVII)
Kimahri (FFX)
Rikku (FFX)
Eiko (FFIX)


Dorkiest

Butz (FFV)
Aeris (FFVII)
Quistis (FFVIII)
Steiner (FFIX)

(Ive only played FFV,VII,VIII,IX and X so i can only compare characters from those games)