I'd say Ninetales works for a magician/wizard/ect. themed run, and maybe some of the others below. Gallade is probably more of a warrior though.
Ninetales -- Pokedex entry "Legend has it that Ninetales came into being when nine wizards possessing sacred powers merged into one. This Pokémon is highly intelligent—it can understand human speech." Plus the whole mind control shtick.
Blissey -- Probably would only work if you count "healers" as mages.
Espeon -- Mind control, predictions.
Gengar -- Might work because of its connection to curses, and looking vaguely humanoid. But then again, most ghost types can learn curse, so...
Banette -- Same thing as Gengar.
Dusclops/Dusknoir -- Connection to will-o-wisps, spectral fire, and mind control.
Froslass -- Based off the Japanese yuki-onna. She might be a witch.
For magic, maybe only choose the Pokemon with a strong connection to magic.
Examples: Clefable, Starmie, Ledian, Togekiss, Banette, Chimecho, Musharna, Sigilyph
Although if you decided to go with the guardians theme (like Golett) Sigilyph and Cofagrigus would work.
Good luck on your run! It seems very interesting.