Cloud: Drain strike 6/ Double cut 6 (Veil of Protection)
Seph: Retaliate 6 / Power break 6 (Stunner)
Tidus: Double cut 4 / Armour break 4 (Delay Attack)
Red: Slow 6 / Boost 10 (Lunatic High)
Garnet: Curaga 10 / Protectga 2 (Mystic Prayer)
RW: Sentinel Grimoire
Boss 1 - Breaks on boss and auto attack with boost. Easy kill. No medals lost.
Boss 2 - I gambled with attacking only as I didn't bring magic. Enter retaliate, didn't take long but if you can swing magic it's best. 1 medal lost.
Boss 3 - This one was pretty bad in that he made me use most of my abilities. Break, retaliate, boost, and slow. 3 medals lost.
Boss 4 - The real deal. I used a mythril and unloaded everything. Used boosts on Seph and Cloud exclusively and kept the boss slowed at all costs. Delay attack with High scorer is a god send. Basically just keep your defenses up, stay topped up, and it will end before you know it. 3 medals lost.
Hope that helps, my Seph was doing about 2800 - 3000 dmg with this strategy and whenever using abilities damage would range from 4000 - 6000 depending on the character plus breaks and boosts applied. Good luck all who attempt this run!