Thanks for sharing your setup. I just wanted to add that Oalston is indispensable for bosses as well as for random mobs once he has learned Meteo and Ultima. You can choose to teach Oalston one of these spells by completing a certain side quest, and my guess is that Oalston learns the other one when reaching level 99. I gave him Meteo after completing the side quest, and then he learned Ultima when reaching level 99, but I don't know if it works the other way around.
Meteo is a 5-hit Fire elemental spell against a single target, and if a max-magic (2000) Oalston is up against a boss without any Fire resistance, he can easily inflict 50000+ damage each turn. Ultima hits all enemies with non-elemental damage, which easily adds up to 20000+ damage when used by a max-magic (2000) Oalston, who is already a valuable asset against random mobs even before learning Ultima (once he learns Apocalpyse, which isn't that much weaker, but an Earth-elemental skill, which makes it useless against certain enemies). I can't imagine traveling the game's world without these two spells ever again.