Depends on where the fights are. If Earth, then Remnant is completely screwed over; only things they would actually have are their semblances. If Remnant, Earth still wins, but the margin of victory will be narrower. Remnant would have the advantage of Dust, terrain knowledge, and Grimm, but they don't have anything real dangerous against Terran military technology. Dust can be understood. Terrain knowledge can move to the Terran side. Grimm are a third-party factor that would provide some trouble.