EMT, RMC and IMC are all acceptable equipment grounding conductors. See NEC 250.118.
FMC is only acceptable for use as a EGC when the sum of all lengths used to furnish a ground path in a circuit is less than 6 feet. Beyond 6 feet you need to pull a EGC or use MC.
What all that gibberish means is if your powerbridge is less than 6 feet long, you can use FMC (aka "greenfield", "bx") with no need to pull a ground (green or bare copper wire). Beyond 6 feet, you'll be pulling black, white and green. Or just use MC cable, which has a green EGC inside the armor already.
Subject to local amendments.. but I've never heard of any.