The Fighting Shadow Team is an unofficial term given to the opponents faced on the Multi-Man Mode.

The Fighting Shadow Team members are basically gray-shaded versions of the original 28 playable characters, having all the attacks and moves from the originals, but weaker and unintelligent, meaning they are easy to defeat.

It could also said that there are unlockable Shadow members, obviously referred to the unlockable characters shadow counterparts unlocked once the original character is unlocked.