We'll start with Hugh -
People claim Hugh is useless because his spells aren't all that powerful - What about SaGen ? It can wipe the bio's on a screen clean, and Vol, it destroys a bio monster and a magical monster for about 570 damage, and SaVol does about 1000 damage to them!
Shir - Despite stealing, she has a major use! NaGra! She also has Hinas and Ryuka, if you're in a dungeon before you have the Nei-Sword, Rolf could run out of TP, and if you're not using her techs often, she can use it!