>>2021965Besides the above, if you're running into trouble selecting costumes in Versus/the normal character selection screens (which is where you're able to select different hairstyles, etc., with a preview): assuming you have everything installed properly--hitting '2' (tanned option) should make all the preview buttons swap over to swimsuits. You may, however, have to switch to a different character and back. Hitting '1' (no tan) should bring back the default outfits)--this is useful for figuring out what swimsuit option corresponds to which DLC costume slot.
Hopefully that helps you out a little bit. As the above said, you choose them in 'Versus', save it with (CTRL+No.), then hit (No.) by itself to recall it in theater mode (and hope it works--Autolink still gets confused a lot).