It would be specific to individual games. Hosts will typically outline rules for each team RE camo so that players can tell one another apart with relative ease.
Usually you see games split up as Tan side vs Green side. Also other games will do camo vs civvy or sometimes you used to see digital vs analog camo.
If all-black is your teams choice of BDU you may find yourself having to purchase something else depending on what game you attend. To start out though and for attending skrims and other laid back matches an all-black BDU shouldn't be a problem typically.