Thanks for the replies all.
To clarify, all six strobes need to fire at the same time, for a set amount of time. It's a last minute prop for a one-time live event so I'm keen to keep it as quick and dirty as possible.
My plan was to get three 12V batteries connected via mosfets to the arduino, with two strobes per battery. Will this work ok? Is it as straight forward as I'm making it out to be? My electronics knowledge is awful, so I'm aware that I might be getting it totally wrong.