Definitely doable for the event.
I've been farming up Executioner to replace Phasma in my arena team, but lately I'm wondering if I should keep her in. You don't need her leadership, and her AoE doesn't hit very hard (the speed down is nice though), but her Victory March special really helps to keep the TM/Advantage flowing. I find my opponent rarely gets to attack by the time the fight is over.
I don't have FOST, but I imagine his taunt granting TM to everyone works in a similar fashion.