For me, mage teams are all about using a roaming warrior's BSB for nuking. Raines or Maria are the general purpose RW for damage, or when you're targetting a weakness you RW stuff like Ashe, Papalymo, Quistis etc, depending on the needed element.
Using the RW to go directly into burst mode without having to rely on the weakness of mages poor soulbreak generation, mage teams can do explosive damage right out of the gate (use mako/dr mog on your buffers like Onion or Krile). Then if the boss is still alive when the roaming BSB wears off (which is rare), by then you've built up some soulbreaks, and then you unleash your mages OSB or whatever to finish the fight.
With the above, you can also use record materia like devotion or scholars determination for even more damage, instead of 0 dps record materias like battleforged for SB gen.