So in a campaign, if you fly a russian aircraft and come up against axis they will have the default skins, and if you fly axis and see other friendly squadrons they will have the default skin and you can only change your own/own groups..?
This depends on mission maker, he can set custom skins for planes in their campaigns and provide this skins together with mission files.
In MP is like J.Redd say, for see that 1945 Western Front "badass ace" skin or one based on football team shirt that some people prefer use - instead a skin appropriated for that scenery/era - you need download this skin and place in skin folder of your game install.
