GBA version is the one to do a challenge. Are you doing a solo WM challenge, or a party of WM? Will you upgrade them to White Wizards?
ive been playing for 3 hours and im at the fight against Astos. im using 4 WM and probably will get white wizards. i just hope that i get some better weapons. it doesnt help that i have that 1 WM that always dies though! lol